* This is a sample main program for twpbvp, a fortran 77 package * for solving two-point boundary value problems, written by * J.R Cash and M.H. Wright. The code is fully documented * in the user's guide, available as a LaTeX file from netlib. * Machine precision is provided automatically via netlib * (in the routine d1mach). * Questions should be directed to Professor Jeff Cash, Department * of Mathematics, Imperial College, London SW7 2BZ, United Kingdom, * email j.cash@ic.ac.uk. implicit double precision (a-h,o-z) dimension fixpnt(2), ltol(2), tol(2) dimension u(2, 1000), xx(1000) dimension wrk(10000), iwrk(6000) character*30 pname logical linear, giveu, givmsh external fsub, dfsub, gsub, dgsub common/counts/nfcall * The value of eps represents the parameter epsilon * appearing in the test problem. common/probs/eps, pi logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 * double precision datan parameter (one = 1.0d+0, zero = 0.0d+0, ten = 10.0d+0) nfcall = 0 pi = 4.0d+0*datan(one) * pname = problem name pname = 'Test problem with eps = .01' eps = 1.0d-2 nudim = 2 lwrkfl = 10000 lwrkin = 6000 ncomp = 2 nlbc = 1 ntol = 1 ltol(1) = 1 tol(1) = 0.01 nfxpnt = 0 aleft = zero aright = one linear = .false. giveu = .false. givmsh = .false. write(6,771) pname write(6,772) ncomp, nlbc, ntol write(6,773) aleft, aright if (linear) write (6,774) if (.not. linear) write(6,775) if (nfxpnt .gt. 0) write(6,776) nfxpnt write(6,777) (ltol(i), i=1,ntol) write(6,778) (tol(i), i=1,ntol) call twpbvp(ncomp, nlbc, aleft, aright, * nfxpnt, fixpnt, ntol, ltol, tol, * linear, givmsh, giveu, nmsh, * xx, nudim, u, nmax, * lwrkfl, wrk, lwrkin, iwrk, * fsub, dfsub, gsub, dgsub, iflbvp) if (iflbvp .eq. 0) then write(6,901) nmsh write(6,902) if (nmsh .lt. 25) then iminc = 1 elseif (nmsh .lt. 75) then iminc = 5 elseif (nmsh .lt. 200) then iminc = 10 elseif (nmsh .lt. 1000) then iminc = 20 else iminc = 50 endif do 100 i = 1, nmsh-1, iminc write(6,900) i, xx(i), (u(j,i), j=1,ncomp) 100 continue write(6,900) nmsh, xx(nmsh), (u(j,nmsh), j=1,ncomp) endif if(iflbvp .eq. -1) then write(6,903) endif stop 771 format(1h ,a30) 772 format(1h ,'ncomp=',i5,5x,'nlbc=',i5,5x,'ntol=',i5) 773 format(1h ,'aleft =',1pe11.3,5x,'aright=',1pe11.3) 774 format(1h ,'solved as a linear problem') 775 format(1h ,'solved as a nonlinear problem') 776 format(1h ,'nfxpnt =',i5) 777 format(1h ,'ltol',5x,5i5) 778 format(1h ,'tolerances',5(1pe11.3)) 900 format(1h ,i4,5(1pe14.6)) 901 format(/, 1h ,'final solution, nmsh =',i8,/) 902 format(1h ,3x,'i',2x,'mesh point',8x,'u(1)',10x,'u(2)') 903 format(1h ,'error in the input parameters') end subroutine fsub(ncomp, x, u, f) * part of sample test function for code twpbvp, for two-point * boundary value problems. This example is documented in the * user's guide for twpbvp, a LaTeX file available from netlib. * It is called `nonlinear problem 1'. implicit double precision (a-h,o-z) dimension u(*), f(*) common/probs/eps, pi parameter (half = 0.5d+0, two = 2.0d+0) * double precision exp, sin common/counts/nfcall nfcall = nfcall + 1 * nonlinear problem 1 f(1) = u(2) f(2) = (-exp(u(1))*u(2) + * half*pi*sin(half*pi*x)*exp(two*u(1)))/eps return end subroutine dfsub(ncomp, x, u, df) * part of sample test function for code twpbvp, for two-point * boundary value problems. This example is documented in the * user's guide for twpbvp, a LaTeX file available from netlib. implicit double precision (a-h,o-z) dimension u(*), df(ncomp,*) common/probs/eps, pi parameter (half = 0.5d+0, one = 1.0d+0, zero = 0.0d+0) parameter (two = 2.0d+0) * double precision exp, sin df(1,1) = zero df(1,2) = one df(2,1) = -(exp(u(1))*u(2) * - pi*sin(pi*half*x)*exp(two*u(1)))/eps df(2,2) = -exp(u(1))/eps return end subroutine gsub(i, ncomp, u, g) * part of sample test function for code twpbvp, for two-point * boundary value problems. This example is documented in the * user's guide for twpbvp, a LaTeX file available from netlib. implicit double precision (a-h,o-z) dimension u(*) g = u(1) return end subroutine dgsub(i, ncomp, u, dg) * part of sample test function for code twpbvp, for two-point * boundary value problems. This example is documented in the * user's guide for twpbvp, a LaTeX file available from netlib. implicit double precision (a-h,o-z) dimension u(*), dg(*) parameter (one = 1.0d+0, zero = 0.0d+0) dg(1) = one dg(2) = zero return end c This is the code that has gone into netlib as a replacement. DOUBLE PRECISION FUNCTION D1MACH(I) INTEGER I C C DOUBLE-PRECISION MACHINE CONSTANTS C C D1MACH( 1) = B**(EMIN-1), THE SMALLEST POSITIVE MAGNITUDE. C C D1MACH( 2) = B**EMAX*(1 - B**(-T)), THE LARGEST MAGNITUDE. C C D1MACH( 3) = B**(-T), THE SMALLEST RELATIVE SPACING. C C D1MACH( 4) = B**(1-T), THE LARGEST RELATIVE SPACING. C C D1MACH( 5) = LOG10(B) C C TO ALTER THIS FUNCTION FOR A PARTICULAR ENVIRONMENT, C THE DESIRED SET OF DATA STATEMENTS SHOULD BE ACTIVATED BY C REMOVING THE C FROM COLUMN 1. C ON RARE MACHINES A STATIC STATEMENT MAY NEED TO BE ADDED. C (BUT PROBABLY MORE SYSTEMS PROHIBIT IT THAN REQUIRE IT.) C C FOR IEEE-ARITHMETIC MACHINES (BINARY STANDARD), ONE OF THE FIRST C TWO SETS OF CONSTANTS BELOW SHOULD BE APPROPRIATE. IF YOU DO NOT C KNOW WHICH SET TO USE, TRY BOTH AND SEE WHICH GIVES PLAUSIBLE C VALUES. C C WHERE POSSIBLE, DECIMAL, OCTAL OR HEXADECIMAL CONSTANTS ARE USED C TO SPECIFY THE CONSTANTS EXACTLY. SOMETIMES THIS REQUIRES USING C EQUIVALENT INTEGER ARRAYS. IF YOUR COMPILER USES HALF-WORD C INTEGERS BY DEFAULT (SOMETIMES CALLED INTEGER*2), YOU MAY NEED TO C CHANGE INTEGER TO INTEGER*4 OR OTHERWISE INSTRUCT YOUR COMPILER C TO USE FULL-WORD INTEGERS IN THE NEXT 5 DECLARATIONS. C C COMMENTS JUST BEFORE THE END STATEMENT (LINES STARTING WITH *) C GIVE C SOURCE FOR D1MACH. C INTEGER SMALL(2) INTEGER LARGE(2) INTEGER RIGHT(2) INTEGER DIVER(2) INTEGER LOG10(2) INTEGER SC, CRAY1(38), J COMMON /D9MACH/ CRAY1 C/6S C/7S SAVE SMALL, LARGE, RIGHT, DIVER, LOG10, SC C/ DOUBLE PRECISION DMACH(5) C EQUIVALENCE (DMACH(1),SMALL(1)) EQUIVALENCE (DMACH(2),LARGE(1)) EQUIVALENCE (DMACH(3),RIGHT(1)) EQUIVALENCE (DMACH(4),DIVER(1)) EQUIVALENCE (DMACH(5),LOG10(1)) C C MACHINE CONSTANTS FOR BIG-ENDIAN IEEE ARITHMETIC (BINARY FORMAT) C MACHINES IN WHICH THE MOST SIGNIFICANT BYTE IS STORED FIRST, C SUCH AS THE AT&T 3B SERIES, MOTOROLA 68000 BASED MACHINES (E.G. C SUN 3), AND MACHINES THAT USE SPARC, HP, OR IBM RISC CHIPS. C C DATA SMALL(1),SMALL(2) / 1048576, 0 / C DATA LARGE(1),LARGE(2) / 2146435071, -1 / C DATA RIGHT(1),RIGHT(2) / 1017118720, 0 / C DATA DIVER(1),DIVER(2) / 1018167296, 0 / C DATA LOG10(1),LOG10(2) / 1070810131, 1352628735 /, SC/987/ C C MACHINE CONSTANTS FOR LITTLE-ENDIAN (BINARY) IEEE ARITHMETIC C MACHINES IN WHICH THE LEAST SIGNIFICANT BYTE IS STORED FIRST, C E.G. IBM PCS AND OTHER MACHINES THAT USE INTEL 80X87 OR DEC C ALPHA CHIPS. C C DATA SMALL(1),SMALL(2) / 0, 1048576 / C DATA LARGE(1),LARGE(2) / -1, 2146435071 / C DATA RIGHT(1),RIGHT(2) / 0, 1017118720 / C DATA DIVER(1),DIVER(2) / 0, 1018167296 / C DATA LOG10(1),LOG10(2) / 1352628735, 1070810131 /, SC/987/ C C MACHINE CONSTANTS FOR AMDAHL MACHINES. C C DATA SMALL(1),SMALL(2) / 1048576, 0 / C DATA LARGE(1),LARGE(2) / 2147483647, -1 / C DATA RIGHT(1),RIGHT(2) / 856686592, 0 / C DATA DIVER(1),DIVER(2) / 873463808, 0 / C DATA LOG10(1),LOG10(2) / 1091781651, 1352628735 /, SC/987/ C C MACHINE CONSTANTS FOR THE BURROUGHS 1700 SYSTEM. C C DATA SMALL(1) / ZC00800000 / C DATA SMALL(2) / Z000000000 / C C DATA LARGE(1) / ZDFFFFFFFF / C DATA LARGE(2) / ZFFFFFFFFF / C C DATA RIGHT(1) / ZCC5800000 / C DATA RIGHT(2) / Z000000000 / C C DATA DIVER(1) / ZCC6800000 / C DATA DIVER(2) / Z000000000 / C C DATA LOG10(1) / ZD00E730E7 / C DATA LOG10(2) / ZC77800DC0 /, SC/987/ C C MACHINE CONSTANTS FOR THE BURROUGHS 5700 SYSTEM. C C DATA SMALL(1) / O1771000000000000 / C DATA SMALL(2) / O0000000000000000 / C C DATA LARGE(1) / O0777777777777777 / C DATA LARGE(2) / O0007777777777777 / C C DATA RIGHT(1) / O1461000000000000 / C DATA RIGHT(2) / O0000000000000000 / C C DATA DIVER(1) / O1451000000000000 / C DATA DIVER(2) / O0000000000000000 / C C DATA LOG10(1) / O1157163034761674 / C DATA LOG10(2) / O0006677466732724 /, SC/987/ C C MACHINE CONSTANTS FOR THE BURROUGHS 6700/7700 SYSTEMS. C C DATA SMALL(1) / O1771000000000000 / C DATA SMALL(2) / O7770000000000000 / C C DATA LARGE(1) / O0777777777777777 / C DATA LARGE(2) / O7777777777777777 / C C DATA RIGHT(1) / O1461000000000000 / C DATA RIGHT(2) / O0000000000000000 / C C DATA DIVER(1) / O1451000000000000 / C DATA DIVER(2) / O0000000000000000 / C C DATA LOG10(1) / O1157163034761674 / C DATA LOG10(2) / O0006677466732724 /, SC/987/ C C MACHINE CONSTANTS FOR FTN4 ON THE CDC 6000/7000 SERIES. C C DATA SMALL(1) / 00564000000000000000B / C DATA SMALL(2) / 00000000000000000000B / C C DATA LARGE(1) / 37757777777777777777B / C DATA LARGE(2) / 37157777777777777774B / C C DATA RIGHT(1) / 15624000000000000000B / C DATA RIGHT(2) / 00000000000000000000B / C C DATA DIVER(1) / 15634000000000000000B / C DATA DIVER(2) / 00000000000000000000B / C C DATA LOG10(1) / 17164642023241175717B / C DATA LOG10(2) / 16367571421742254654B /, SC/987/ C C MACHINE CONSTANTS FOR FTN5 ON THE CDC 6000/7000 SERIES. C C DATA SMALL(1) / O"00564000000000000000" / C DATA SMALL(2) / O"00000000000000000000" / C C DATA LARGE(1) / O"37757777777777777777" / C DATA LARGE(2) / O"37157777777777777774" / C C DATA RIGHT(1) / O"15624000000000000000" / C DATA RIGHT(2) / O"00000000000000000000" / C C DATA DIVER(1) / O"15634000000000000000" / C DATA DIVER(2) / O"00000000000000000000" / C C DATA LOG10(1) / O"17164642023241175717" / C DATA LOG10(2) / O"16367571421742254654" /, SC/987/ C C MACHINE CONSTANTS FOR CONVEX C-1 C C DATA SMALL(1),SMALL(2) / '00100000'X, '00000000'X / C DATA LARGE(1),LARGE(2) / '7FFFFFFF'X, 'FFFFFFFF'X / C DATA RIGHT(1),RIGHT(2) / '3CC00000'X, '00000000'X / C DATA DIVER(1),DIVER(2) / '3CD00000'X, '00000000'X / C DATA LOG10(1),LOG10(2) / '3FF34413'X, '509F79FF'X /, SC/987/ C C MACHINE CONSTANTS FOR THE CRAY 1, XMP, 2, AND 3. C C DATA SMALL(1) / 201354000000000000000B / C DATA SMALL(2) / 000000000000000000000B / C C DATA LARGE(1) / 577767777777777777777B / C DATA LARGE(2) / 000007777777777777776B / C C DATA RIGHT(1) / 376434000000000000000B / C DATA RIGHT(2) / 000000000000000000000B / C C DATA DIVER(1) / 376444000000000000000B / C DATA DIVER(2) / 000000000000000000000B / C C DATA LOG10(1) / 377774642023241175717B / C DATA LOG10(2) / 000007571421742254654B /, SC/987/ C C MACHINE CONSTANTS FOR THE DATA GENERAL ECLIPSE S/200 C C SMALL, LARGE, RIGHT, DIVER, LOG10 SHOULD BE DECLARED C INTEGER SMALL(4), LARGE(4), RIGHT(4), DIVER(4), LOG10(4) C C NOTE - IT MAY BE APPROPRIATE TO INCLUDE THE FOLLOWING LINE - C STATIC DMACH(5) C C DATA SMALL/20K,3*0/,LARGE/77777K,3*177777K/ C DATA RIGHT/31420K,3*0/,DIVER/32020K,3*0/ C DATA LOG10/40423K,42023K,50237K,74776K/, SC/987/ C C MACHINE CONSTANTS FOR THE HARRIS SLASH 6 AND SLASH 7 C C DATA SMALL(1),SMALL(2) / '20000000, '00000201 / C DATA LARGE(1),LARGE(2) / '37777777, '37777577 / C DATA RIGHT(1),RIGHT(2) / '20000000, '00000333 / C DATA DIVER(1),DIVER(2) / '20000000, '00000334 / C DATA LOG10(1),LOG10(2) / '23210115, '10237777 /, SC/987/ C C MACHINE CONSTANTS FOR THE HONEYWELL DPS 8/70 SERIES. C C DATA SMALL(1),SMALL(2) / O402400000000, O000000000000 / C DATA LARGE(1),LARGE(2) / O376777777777, O777777777777 / C DATA RIGHT(1),RIGHT(2) / O604400000000, O000000000000 / C DATA DIVER(1),DIVER(2) / O606400000000, O000000000000 / C DATA LOG10(1),LOG10(2) / O776464202324, O117571775714 /, SC/987/ C C MACHINE CONSTANTS FOR THE IBM 360/370 SERIES, C THE XEROX SIGMA 5/7/9 AND THE SEL SYSTEMS 85/86. C C DATA SMALL(1),SMALL(2) / Z00100000, Z00000000 / C DATA LARGE(1),LARGE(2) / Z7FFFFFFF, ZFFFFFFFF / C DATA RIGHT(1),RIGHT(2) / Z33100000, Z00000000 / C DATA DIVER(1),DIVER(2) / Z34100000, Z00000000 / C DATA LOG10(1),LOG10(2) / Z41134413, Z509F79FF /, SC/987/ C C MACHINE CONSTANTS FOR THE INTERDATA 8/32 C WITH THE UNIX SYSTEM FORTRAN 77 COMPILER. C C FOR THE INTERDATA FORTRAN VII COMPILER REPLACE C THE Z'S SPECIFYING HEX CONSTANTS WITH Y'S. C C DATA SMALL(1),SMALL(2) / Z'00100000', Z'00000000' / C DATA LARGE(1),LARGE(2) / Z'7EFFFFFF', Z'FFFFFFFF' / C DATA RIGHT(1),RIGHT(2) / Z'33100000', Z'00000000' / C DATA DIVER(1),DIVER(2) / Z'34100000', Z'00000000' / C DATA LOG10(1),LOG10(2) / Z'41134413', Z'509F79FF' /, SC/987/ C C MACHINE CONSTANTS FOR THE PDP-10 (KA PROCESSOR). C C DATA SMALL(1),SMALL(2) / "033400000000, "000000000000 / C DATA LARGE(1),LARGE(2) / "377777777777, "344777777777 / C DATA RIGHT(1),RIGHT(2) / "113400000000, "000000000000 / C DATA DIVER(1),DIVER(2) / "114400000000, "000000000000 / C DATA LOG10(1),LOG10(2) / "177464202324, "144117571776 /, SC/987/ C C MACHINE CONSTANTS FOR THE PDP-10 (KI PROCESSOR). C C DATA SMALL(1),SMALL(2) / "000400000000, "000000000000 / C DATA LARGE(1),LARGE(2) / "377777777777, "377777777777 / C DATA RIGHT(1),RIGHT(2) / "103400000000, "000000000000 / C DATA DIVER(1),DIVER(2) / "104400000000, "000000000000 / C DATA LOG10(1),LOG10(2) / "177464202324, "047674776746 /, SC/987/ C C MACHINE CONSTANTS FOR PDP-11 FORTRANS SUPPORTING C 32-BIT INTEGERS (EXPRESSED IN INTEGER AND OCTAL). C C DATA SMALL(1),SMALL(2) / 8388608, 0 / C DATA LARGE(1),LARGE(2) / 2147483647, -1 / C DATA RIGHT(1),RIGHT(2) / 612368384, 0 / C DATA DIVER(1),DIVER(2) / 620756992, 0 / C DATA LOG10(1),LOG10(2) / 1067065498, -2063872008 /, SC/987/ C C DATA SMALL(1),SMALL(2) / O00040000000, O00000000000 / C DATA LARGE(1),LARGE(2) / O17777777777, O37777777777 / C DATA RIGHT(1),RIGHT(2) / O04440000000, O00000000000 / C DATA DIVER(1),DIVER(2) / O04500000000, O00000000000 / C DATA LOG10(1),LOG10(2) / O07746420232, O20476747770 /, SC/987/ C C MACHINE CONSTANTS FOR PDP-11 FORTRANS SUPPORTING C 16-BIT INTEGERS (EXPRESSED IN INTEGER AND OCTAL). C C SMALL, LARGE, RIGHT, DIVER, LOG10 SHOULD BE DECLARED C INTEGER SMALL(4), LARGE(4), RIGHT(4), DIVER(4), LOG10(4) C C DATA SMALL(1),SMALL(2) / 128, 0 / C DATA SMALL(3),SMALL(4) / 0, 0 / C C DATA LARGE(1),LARGE(2) / 32767, -1 / C DATA LARGE(3),LARGE(4) / -1, -1 / C C DATA RIGHT(1),RIGHT(2) / 9344, 0 / C DATA RIGHT(3),RIGHT(4) / 0, 0 / C C DATA DIVER(1),DIVER(2) / 9472, 0 / C DATA DIVER(3),DIVER(4) / 0, 0 / C C DATA LOG10(1),LOG10(2) / 16282, 8346 / C DATA LOG10(3),LOG10(4) / -31493, -12296 /, SC/987/ C C DATA SMALL(1),SMALL(2) / O000200, O000000 / C DATA SMALL(3),SMALL(4) / O000000, O000000 / C C DATA LARGE(1),LARGE(2) / O077777, O177777 / C DATA LARGE(3),LARGE(4) / O177777, O177777 / C C DATA RIGHT(1),RIGHT(2) / O022200, O000000 / C DATA RIGHT(3),RIGHT(4) / O000000, O000000 / C C DATA DIVER(1),DIVER(2) / O022400, O000000 / C DATA DIVER(3),DIVER(4) / O000000, O000000 / C C DATA LOG10(1),LOG10(2) / O037632, O020232 / C DATA LOG10(3),LOG10(4) / O102373, O147770 /, SC/987/ C C MACHINE CONSTANTS FOR THE PRIME 50 SERIES SYSTEMS C WITH 32-BIT INTEGERS AND 64V MODE INSTRUCTIONS, C SUPPLIED BY IGOR BRAY. C C DATA SMALL(1),SMALL(2) / :10000000000, :00000100001 / C DATA LARGE(1),LARGE(2) / :17777777777, :37777677775 / C DATA RIGHT(1),RIGHT(2) / :10000000000, :00000000122 / C DATA DIVER(1),DIVER(2) / :10000000000, :00000000123 / C DATA LOG10(1),LOG10(2) / :11504046501, :07674600177 /, SC/987/ C C MACHINE CONSTANTS FOR THE SEQUENT BALANCE 8000 C C DATA SMALL(1),SMALL(2) / $00000000, $00100000 / C DATA LARGE(1),LARGE(2) / $FFFFFFFF, $7FEFFFFF / C DATA RIGHT(1),RIGHT(2) / $00000000, $3CA00000 / C DATA DIVER(1),DIVER(2) / $00000000, $3CB00000 / C DATA LOG10(1),LOG10(2) / $509F79FF, $3FD34413 /, SC/987/ C C MACHINE CONSTANTS FOR THE UNIVAC 1100 SERIES. C C DATA SMALL(1),SMALL(2) / O000040000000, O000000000000 / C DATA LARGE(1),LARGE(2) / O377777777777, O777777777777 / C DATA RIGHT(1),RIGHT(2) / O170540000000, O000000000000 / C DATA DIVER(1),DIVER(2) / O170640000000, O000000000000 / C DATA LOG10(1),LOG10(2) / O177746420232, O411757177572 /, SC/987/ C C MACHINE CONSTANTS FOR THE VAX UNIX F77 COMPILER C C DATA SMALL(1),SMALL(2) / 128, 0 / C DATA LARGE(1),LARGE(2) / -32769, -1 / C DATA RIGHT(1),RIGHT(2) / 9344, 0 / C DATA DIVER(1),DIVER(2) / 9472, 0 / C DATA LOG10(1),LOG10(2) / 546979738, -805796613 /, SC/987/ C C MACHINE CONSTANTS FOR THE VAX-11 WITH C FORTRAN IV-PLUS COMPILER C C DATA SMALL(1),SMALL(2) / Z00000080, Z00000000 / C DATA LARGE(1),LARGE(2) / ZFFFF7FFF, ZFFFFFFFF / C DATA RIGHT(1),RIGHT(2) / Z00002480, Z00000000 / C DATA DIVER(1),DIVER(2) / Z00002500, Z00000000 / C DATA LOG10(1),LOG10(2) / Z209A3F9A, ZCFF884FB /, SC/987/ C C MACHINE CONSTANTS FOR VAX/VMS VERSION 2.2 C C DATA SMALL(1),SMALL(2) / '80'X, '0'X / C DATA LARGE(1),LARGE(2) / 'FFFF7FFF'X, 'FFFFFFFF'X / C DATA RIGHT(1),RIGHT(2) / '2480'X, '0'X / C DATA DIVER(1),DIVER(2) / '2500'X, '0'X / C DATA LOG10(1),LOG10(2) / '209A3F9A'X, 'CFF884FB'X /, SC/987/ C C *** ISSUE STOP 779 IF ALL DATA STATEMENTS ARE COMMENTED... IF (SC .NE. 987) THEN DMACH(1) = 1.D13 IF ( SMALL(1) .EQ. 1117925532 * .AND. SMALL(2) .EQ. -448790528) THEN * *** IEEE BIG ENDIAN *** SMALL(1) = 1048576 SMALL(2) = 0 LARGE(1) = 2146435071 LARGE(2) = -1 RIGHT(1) = 1017118720 RIGHT(2) = 0 DIVER(1) = 1018167296 DIVER(2) = 0 LOG10(1) = 1070810131 LOG10(2) = 1352628735 ELSE IF ( SMALL(2) .EQ. 1117925532 * .AND. SMALL(1) .EQ. -448790528) THEN * *** IEEE LITTLE ENDIAN *** SMALL(2) = 1048576 SMALL(1) = 0 LARGE(2) = 2146435071 LARGE(1) = -1 RIGHT(2) = 1017118720 RIGHT(1) = 0 DIVER(2) = 1018167296 DIVER(1) = 0 LOG10(2) = 1070810131 LOG10(1) = 1352628735 ELSE IF ( SMALL(1) .EQ. -2065213935 * .AND. SMALL(2) .EQ. 10752) THEN * *** VAX WITH D_FLOATING *** SMALL(1) = 128 SMALL(2) = 0 LARGE(1) = -32769 LARGE(2) = -1 RIGHT(1) = 9344 RIGHT(2) = 0 DIVER(1) = 9472 DIVER(2) = 0 LOG10(1) = 546979738 LOG10(2) = -805796613 ELSE IF ( SMALL(1) .EQ. 1267827943 * .AND. SMALL(2) .EQ. 704643072) THEN * *** IBM MAINFRAME *** SMALL(1) = 1048576 SMALL(2) = 0 LARGE(1) = 2147483647 LARGE(2) = -1 RIGHT(1) = 856686592 RIGHT(2) = 0 DIVER(1) = 873463808 DIVER(2) = 0 LOG10(1) = 1091781651 LOG10(2) = 1352628735 ELSE IF ( SMALL(1) .EQ. 1120022684 * .AND. SMALL(2) .EQ. -448790528) THEN * *** CONVEX C-1 *** SMALL(1) = 1048576 SMALL(2) = 0 LARGE(1) = 2147483647 LARGE(2) = -1 RIGHT(1) = 1019215872 RIGHT(2) = 0 DIVER(1) = 1020264448 DIVER(2) = 0 LOG10(1) = 1072907283 LOG10(2) = 1352628735 ELSE IF ( SMALL(1) .EQ. 815547074 * .AND. SMALL(2) .EQ. 58688) THEN * *** VAX G-FLOATING *** SMALL(1) = 16 SMALL(2) = 0 LARGE(1) = -32769 LARGE(2) = -1 RIGHT(1) = 15552 RIGHT(2) = 0 DIVER(1) = 15568 DIVER(2) = 0 LOG10(1) = 1142112243 LOG10(2) = 2046775455 ELSE DMACH(2) = 1.D27 + 1 DMACH(3) = 1.D27 LARGE(2) = LARGE(2) - RIGHT(2) IF (LARGE(2) .EQ. 64 .AND. SMALL(2) .EQ. 0) THEN CRAY1(1) = 67291416 DO 10 J = 1, 20 10 CRAY1(J+1) = CRAY1(J) + CRAY1(J) CRAY1(22) = CRAY1(21) + 321322 DO 20 J = 22, 37 20 CRAY1(J+1) = CRAY1(J) + CRAY1(J) IF (CRAY1(38) .EQ. SMALL(1)) THEN * *** CRAY *** * SMALL(1) = 2332160919536140288 SMALL(1) = 2332160 SMALL(1) = 1000000*SMALL(1) + 919536 SMALL(1) = 1000000*SMALL(1) + 140288 SMALL(2) = 0 * LARGE(1) = 6917247552664371199 LARGE(1) = 6917247 LARGE(1) = 1000000*LARGE(1) + 552664 LARGE(1) = 1000000*LARGE(1) + 371199 * LARGE(2) = 281474976710654 LARGE(2) = 28147497 LARGE(2) = 10000000*LARGE(2) + 6710654 * RIGHT(1) = 4585649583081652224 RIGHT(1) = 4585649 RIGHT(1) = 1000000*RIGHT(1) + 583081 RIGHT(1) = 1000000*RIGHT(1) + 652224 RIGHT(2) = 0 * DIVER(1) = 4585931058058362880 DIVER(1) = 4585931 DIVER(1) = 1000000*DIVER(1) + 058058 DIVER(1) = 1000000*DIVER(1) + 362880 DIVER(2) = 0 * LOG10(1) = 4611574008272714703 LOG10(1) = 4611574 LOG10(1) = 1000000*LOG10(1) + 8272 LOG10(1) = 1000000*LOG10(1) + 714703 * LOG10(2) = 272234615232940 LOG10(2) = 27223461 LOG10(2) = 10000000*LOG10(2) + 5232940 ELSE WRITE(*,9000) STOP 779 END IF ELSE WRITE(*,9000) STOP 779 END IF END IF SC = 987 END IF C C *** ISSUE STOP 778 IF ALL DATA STATEMENTS ARE OBVIOUSLY WRONG... IF (DMACH(4) .GE. 1.0D0) STOP 778 *C/6S *C IF (I .LT. 1 .OR. I .GT. 5) *C 1 CALL SETERR(24HD1MACH - I OUT OF BOUNDS,24,1,2) *C/7S * IF (I .LT. 1 .OR. I .GT. 5) * 1 CALL SETERR('D1MACH - I OUT OF BOUNDS',24,1,2) *C/ IF (I .LT. 1 .OR. I .GT. 5) THEN WRITE(*,*) 'D1MACH(I): I =',I,' is out of bounds.' STOP END IF D1MACH = DMACH(I) RETURN C/6S C9000 FORMAT(/46H Adjust D1MACH by uncommenting data statements/ C *30H appropriate for your machine.) C/7S 9000 FORMAT(/' Adjust D1MACH by uncommenting data statements'/ *' appropriate for your machine.') C/ C * /* C source for D1MACH -- remove the * in column 1 */ *#include *#include *#include * *double d1mach_(long *i) *{ * switch(*i){ * case 1: return DBL_MIN; * case 2: return DBL_MAX; * case 3: return DBL_EPSILON/FLT_RADIX; * case 4: return DBL_EPSILON; * case 5: return log10(FLT_RADIX); * } * * fprintf(stderr, "invalid argument: d1mach(%ld)\n", *i); * exit(1); * return 0; /* for compilers that complain of missing return values */ * } END subroutine sprt(n, array) * sprt prints an array. implicit double precision (a-h,o-z) dimension array(n) write(6,900) (array(i), i=1,n) 900 format(1h ,(7(1pe11.3))) return end subroutine mprt(nrowd, nrow, ncol, array) * mprt prints a matrix. implicit double precision (a-h,o-z) dimension array(nrowd, ncol) do 400 i = 1, nrow write(6,900) i,(array(i,j), j=1,ncol) 400 continue 900 format(1h ,i5,(6(1pe11.3))) return end subroutine twpbvp(ncomp, nlbc, aleft, aright, * nfxpnt, fixpnt, ntol, ltol, tol, * linear, givmsh, giveu, nmsh, * xx, nudim, u, nmax, * lwrkfl, wrk, lwrkin, iwrk, * fsub, dfsub, gsub, dgsub, iflbvp) * subroutine twpbvp is intended to solve two-point boundary * value problems. For information about its use, parameters, * etc., see the user's guide, a LaTeX file available from netlib. implicit double precision (a-h,o-z) dimension fixpnt(*), ltol(*), tol(*) dimension xx(*), u(nudim,*) dimension wrk(lwrkfl), iwrk(lwrkin) logical linear, givmsh, giveu external fsub, dfsub, gsub, dgsub logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 intrinsic abs, min parameter ( zero = 0.0d+0 ) * Check for invalid input parameters. If any parameters are * invalid, exit with the flag iflbvp set to -1. iflbvp = -1 if (ncomp .le. 0) return if (nlbc .lt. 0 .or. nlbc .gt. ncomp) return if (aleft .ge. aright) return if (nfxpnt .lt. 0) return if (givmsh .and. nmsh .lt. nfxpnt+2) return if (givmsh .and. xx(1) .ne. aleft) return if (givmsh .and. xx(nmsh) .ne. aright) return if (nfxpnt .gt. 0) then if (fixpnt(1) .le. aleft) return if (fixpnt(nfxpnt) .ge. aright) return do 50 i = 1, nfxpnt-1 if (fixpnt(i+1) .le. fixpnt(i)) return 50 continue endif if (ntol .lt. 1) return do 60 i = 1, ntol if (ltol(i) .lt. 0 .or. ltol(i) .gt. ncomp) return if (tol(i) .le. zero) return 60 continue if (giveu .and. .not. givmsh) return if (nudim .le. 0) return if (lwrkfl .le. 0 .or. lwrkin .le. 0) return * Calculate maximum number of mesh points possible with the * given floating-point and integer workspace. isp = lwrkfl - 2*ntol - 9*ncomp - 4*ncomp*ncomp iden = 4*ncomp*ncomp + 12*ncomp + 3 nmax1 = isp/iden isp = lwrkin - ncomp nmax2 = isp/(ncomp+2) nmax = min(nmax1, nmax2) if (iprint .ge. 0) write(6,901) nmax 901 format(1h ,'nmax from workspace =',i8) if (nmax .le. 1) return * Partition floating point workspace. irhs = 1 lrhs = ncomp*nmax itpblk = irhs + lrhs ltpblk = ncomp*nlbc ibtblk = itpblk + ltpblk lbtblk = ncomp*(ncomp - Nlbc) iajac = ibtblk + lbtblk lajac = 2*ncomp*ncomp*nmax ibhold = iajac + lajac lbhold = ncomp*ncomp*nmax ichold = ibhold + lbhold lchold = ncomp*ncomp*nmax ifval = ichold + lchold lfval = ncomp*nmax idef = ifval + lfval ldef = ncomp*(nmax-1) idefex = idef + ldef ldefex = ncomp*(nmax-1) * def6 uses the same space as defexp idef6 = idefex ldef6 = ncomp*(nmax-1) idefim = idef6 + ldef6 ldefim = ncomp*(nmax-1) * def8 uses the same space as defimp idef8 = idefim ldef8 = ncomp*(nmax-1) iusve = idef8 + ldef8 lusve = ncomp*nmax iuold = iusve + lusve luold = ncomp*nmax itmrhs = iuold + luold ltmrhs = ncomp*nmax irhtri = itmrhs + ltmrhs lrhtri = ncomp*nmax idelu = irhtri + lrhtri ldelu = ncomp*nmax ixmer = idelu + ldelu lxmer = ncomp*nmax * rerr occupies the same space as xmerit irerr = ixmer lrerr = ncomp*nmax iutri = irerr + lrerr lutri = ncomp*nmax iermx = iutri + lutri lermx = nmax irtdc = iermx + lermx lrtdc = nmax ixxold = irtdc + lrtdc lxxold = nmax iuint = ixxold + lxxold luint = ncomp iftmp = iuint + luint lftmp = ncomp idgtm = iftmp + lftmp ldgtm = ncomp idftm1 = idgtm + ldgtm ldftm1 = ncomp*ncomp idftm2 = idftm1 + ldftm1 ldftm2 = ncomp*ncomp itmp = idftm2 + ldftm2 ltmp = ncomp*8 idsq = itmp + ltmp ldsq = ncomp*ncomp idexr = idsq + ldsq ldexr = ncomp ietst6 = idexr + ldexr letst6 = ntol ietst8 = ietst6 + letst6 letst8 = ntol ilast = ietst8 + letst8 if (iprint .eq. 1) write(6,903) ilast 903 format(1h ,'ilast',i10) * Partition integer workspace. iiref = 1 liref = nmax iihcom = iiref + liref lihcom = nmax iipvbk = iihcom + lihcom lipvbk = ncomp*nmax iipvlu = iipvbk + lipvbk lipvlu = ncomp call bvpsol(ncomp, nmsh, nlbc, aleft, aright, * nfxpnt, fixpnt, ntol, ltol, tol, nmax, linear, * giveu, givmsh, xx, nudim, u, * wrk(idefex), wrk(idefim), wrk(idef), wrk(idelu), * wrk(irhs), wrk(ifval), * wrk(itpblk), wrk(ibtblk), wrk(iajac), wrk(ibhold), * wrk(ichold), iwrk(iipvbk), iwrk(iipvlu), * wrk(iuint), wrk(iftmp), wrk(itmrhs), * wrk(idftm1), wrk(idftm2), wrk(idgtm), * wrk(iutri), wrk(irhtri), wrk(ixmer), * wrk(ixxold), wrk(iuold), wrk(iusve), * wrk(itmp), wrk(idsq), wrk(idexr), wrk(irtdc), * wrk(irerr), wrk(ietst6), wrk(ietst8), wrk(iermx), * iwrk(iihcom), iwrk(iiref), wrk(idef6), wrk(idef8), * fsub,dfsub,gsub,dgsub,iflbvp) return end C----------------------------------------------------------------------- C C C----------------------------------------------------------------------- C SUBROUTINE COLROW (N,TOPBLK,NRWTOP,NOVRLP,ARRAY,NRWBLK,NCLBLK, * NBLOKS,BOTBLK,NRWBOT,PIVOT,B,X,IFLAG) C C*************************************************************** C C THIS PROGRAM SOLVES THE LINEAR SYSTEM A*X = B WHERE A IS C AN ALMOST BLOCK DIAGONAL MATRIX OF THE FORM C C TOPBLK C ARRAY(1) C ARRAY(2) C . C . C . C . C ARRAY(NBLOKS) C BOTBLK C C WHERE C TOPBLK IS NRWTOP BY NOVRLP C ARRAY(K), K=1,NBLOKS, ARE NRWBLK BY NRWBLK+NOVRLP C BOTBLK IS NRWBOT BY NOVRLP, C AND C NOVRLP = NRWTOP + NRWBOT C WITH C NOVRLP.LE.NRWBLK . C C THE LINEAR SYSTEM IS OF ORDER N = NBLOKS*NRWBLK + NOVRLP. C C THE METHOD IMPLEMENTED IS BASED ON GAUSS ELIMINATION WITH C ALTERNATE ROW AND COLUMN ELIMINATION WITH PARTIAL PIVOTING, C WHICH PRODUCES A STABLE DECOMPOSITION OF THE MATRIX A C WITHOUT INTRODUCING FILL-IN. C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C TO OBTAIN A SINGLE PRECISION VERSION OF THIS PACKAGE, REMOVE C ALL DOUBLE PRECISION STATEMENTS. THERE IS ONE SUCH STATEMENT C IN C O L R O W, THREE IN C R D C M P, AND TWO IN C R S O L V. C IN ADDITION, REFERENCES TO BUILT-IN FUNCTIONS DABS AND DMAX1 C MUST BE REPLACED BY DABS AND DMAX1, RESPECTIVELY. ABS OCCURS C NINE TIMES, IN C R D C M P. DMAX1 OCCURS FOUR TIMES, IN C C R D C M P. FINALLY, ZERO IS INITIALISED TO 0.D+0 IN A C DATA STATEMENT IN C R D C M P. THIS MUST BE REPLACED BY: C DATA ZERO/0.0/ C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C ***** PARAMETERS ***** C C *** ON ENTRY ... C C N - INTEGER C THE ORDER OF THE LINEAR SYSTEM, C GIVEN BY NBLOKS*NRWBLK + NOVRLP C C TOPBLK - DOUBLE PRECISION(NRWTOP,NOVRLP) C THE FIRST BLOCK OF THE ALMOST BLOCK C DIAGONAL MATRIX A C C NRWTOP - INTEGER C NUMBER OF ROWS IN THE BLOCK TOPBLK C C NOVRLP - INTEGER C THE NUMBER OF COLUMNS IN WHICH SUCC- C ESSIVE BLOCKS OVERLAP, WHERE C NOVRLP = NRWTOP + NRWBOT C C ARRAY - DOUBLE PRECISION(NRWBLK,NCLBLK,NBLOKS) C ARRAY(,K) CONTAINS THE K-TH NRWBLK C BY NCLBLK BLOCK OF THE MATRIX A C C NRWBLK - INTEGER C NUMBER OF ROWS IN K-TH BLOCK C C NCLBLK - INTEGER C NUMBER OF COLUMNS IN K-TH BLOCK C C NBLOKS - INTEGER C NUMBER OF NRWBLK BY NCLBLK BLOCKS IN C THE MATRIX A C C BOTBLK - DOUBLE PRECISION(NRWBOT,NOVRLP) C THE LAST BLOCK OF THE MATRIX A C C NRWBOT - INTEGER C NUMBER OF ROWS IN THE BLOCK BOTBLK C C PIVOT - INTEGER(N) C WORK SPACE C C B - DOUBLE PRECISION(N) C THE RIGHT HAND SIDE VECTOR C C X - DOUBLE PRECISION(N) C WORK SPACE C C *** ON RETURN ... C C TOPBLK,ARRAY,BOTBLK - ARRAYS CONTAINING THE C DESIRED DECOMPOSITION OF THE MATRIX A C (IF IFLAG = 0) C C PIVOT - INTEGER(N) C RECORDS THE PIVOTING INDICES DETER- C MINED IN THE DECOMPOSITION C C X - DOUBLE PRECISION(N) C THE SOLUTION VECTOR (IF IFLAG = 0) C C IFLAG - INTEGER C = 1, IF INPUT PARAMETERS ARE INVALID C = -1, IF MATRIX IS SINGULAR C = 0, OTHERWISE C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C ***** AUXILIARY PROGRAMS ***** C C CRDCMP(N,TOPBLK,NRWTOP,NOVRLP,ARRAY,NRWBLK,NCLBLK,NBLOKS, C * BOTBLK,NRWBOT,PIVOT,IFLAG) C - DECOMPOSES THE MATRIX A USING MODIFIED C ALTERNATE ROW AND COLUMN ELIMINATON WITH C PARTIAL PIVOTING, AND IS USED FOR THIS C PURPOSE IN C O L R O W. C THE ARGUMENTS ARE AS IN C O L R O W. C C CRSLVE(N,TOPBLK,NRWTOP,NOVRLP,ARRAY,NRWBLK,NCLBLK,NBLOKS, C * BOTBLK,NRWBOT,PIVOT,B,X) C - SOLVES THE SYSTEM A*X = B ONCE A IS DECOMPOSED. C THE ARGUMENTS ARE ALLAS IN C O L R O W. C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C THE SUBROUTINE C O L R O W AUTOMATICALLY SOLVES THE C INPUT SYSTEM WHEN IFLAG=0. C O L R O W IS CALLED ONLY ONCE C FOR A GIVEN SYSTEM. THE SOLUTION FOR A SEQUENCE OF P RIGHT C HAND SIDES CAN BE OBTAINED BY ONE CALL TO C O L R O W AND C P-1 CALLS TO CRSLVE ONLY. SINCE THE ARRAYS TOPBLK,ARRAY, C BOTBLK AND PIVOT CONTAIN THE DECOMPOSITION OF THE GIVEN C COEFFICIENT MATRIX AND PIVOTING INFORMATION ON RETURN FROM C C O L R O W , THEY MUST NOT BE ALTERED BETWEEN SUCCESSIVE C CALLS TO CRSLVE WITH THE SAME LEFT HAND SIDES. FOR THE C SAME REASON, IF THE USER WISHES TO SAVE THE COEFFICIENT C MATRIX, THE ARRAYS TOPBLK,ARRAY,BOTBLK MUST BE COPIED C BEFORE A CALL TO C O L R O W . C C*********************************************************************** C*************************************************************** C IMPLICIT DOUBLE PRECISION(A-H,O-Z) INTEGER PIVOT(1) DIMENSION TOPBLK(NRWTOP,1),ARRAY(NRWBLK,NCLBLK,1),BOTBLK(NRWBOT,1) * ,B(1),X(1) CALL CRDCMP (N,TOPBLK,NRWTOP,NOVRLP,ARRAY,NRWBLK,NCLBLK,NBLOKS, * BOTBLK,NRWBOT,PIVOT,IFLAG) IF (IFLAG.NE.0) RETURN CALL CRSLVE (TOPBLK,NRWTOP,NOVRLP,ARRAY,NRWBLK,NCLBLK,NBLOKS, * BOTBLK,NRWBOT,PIVOT,B,X) RETURN END SUBROUTINE CRDCMP(N,TOPBLK,NRWTOP,NOVRLP,ARRAY,NRWBLK,NCLBLK, * NBLOKS,BOTBLK,NRWBOT,PIVOT,IFLAG) C C*************************************************************** C C C R D C M P DECOMPOSES THE ALMOST BLOCK DIAGONAL MATRIX A C USING MODIFIED ALTERNATE ROW AND COLUMN ELIMINATION WITH C PARTIAL PIVOTING. THE MATRIX A IS STORED IN THE ARRAYS C TOPBLK, ARRAY, AND BOTBLK. C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C ***** PARAMETERS ***** C C *** ON ENTRY ... C C N - INTEGER C THE ORDER OF THE LINEAR SYSTEM, C GIVEN BY NBLOKS*NRWBLK + NOVRLP C C TOPBLK - DOUBLE PRECISION(NRWTOP,NOVRLP) C THE FIRST BLOCK OF THE ALMOST BLOCK C DIAGONAL MATRIX A TO BE DECOMPOSED C C NRWTOP - INTEGER C NUMBER OF ROWS IN THE BLOCK TOPBLK C C NOVRLP - INTEGER C THE NUMBER OF COLUMNS IN WHICH SUCC- C ESSIVE BLOCKS OVERLAP, WHERE C NOVRLP = NRWTOP + NRWBOT C C ARRAY - DOUBLE PRECISION(NRWBLK,NCLBLK,NBLOKS) C ARRAY(,,K) CONTAINS THE K-TH NRWBLK C BY NCLBLK BLOCK OF THE MATRIX A C C NRWBLK - INTEGER C NUMBER OF ROWS IN K-TH BLOCK C C NCLBLK - INTEGER C NUMBER OF COLUMNS IN K-TH BLOCK C C NBLOKS - INTEGER C NUMBER OF NRWBLK BY NCLBLK BLOCKS IN C THE MATRIX A C C BOTBLK - DOUBLE PRECISION(NRWBOT,NOVRLP) C THE LAST BLOCK OF THE MATRIX A C C NRWBOT - INTEGER C NUMBER OF ROWS IN THE BLOCK BOTBLK C C PIVOT - INTEGER(N) C WORK SPACE C C *** ON RETURN ... C C TOPBLK,ARRAY,BOTBLK - ARRAYS CONTAINING THE C DESIRED DECOMPOSITION OF THE MATRIX A C (IF IFLAG = 0) C C PIVOT - INTEGER(N) C RECORDS THE PIVOTING INDICES DETER- C MINED IN THE DECOMPOSITION C C IFLAG - INTEGER C = 1, IF INPUT PARAMETERS ARE INVALID C = -1, IF MATRIX IS SINGULAR C = 0, OTHERWISE C C*************************************************************** C IMPLICIT DOUBLE PRECISION(A-H,O-Z) INTEGER PIVOT(1) DIMENSION TOPBLK(NRWTOP,1),ARRAY(NRWBLK,NCLBLK,1),BOTBLK(NRWBOT,1) DATA ZERO / 0.0D+0 / C C*************************************************************** C C **** DEFINE THE CONSDTANTS USED THROUGHOUT **** C C*************************************************************** C IFLAG = 0 PIVMAX = ZERO NRWTP1 = NRWTOP+1 NROWEL = NRWBLK-NRWTOP NRWEL1 = NROWEL+1 NVRLP0 = NOVRLP-1 C C*************************************************************** C C **** CHECK VALIDITY OF THE INPUT PARAMETERS.... C C IF PARAMETERS ARE INVALID THEN TERMINATE AT 10; C ELSE CONTINUE AT 100. C C*************************************************************** C IF (N.NE.NBLOKS*NRWBLK+NOVRLP) GO TO 10 IF (NOVRLP.NE.NRWTOP+NRWBOT) GO TO 10 IF (NCLBLK.NE.NOVRLP+NRWBLK) GO TO 10 IF (NOVRLP.GT.NRWBLK) GO TO 10 C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C PARAMETERS ARE ACCEPTABLE - CONTINUE AT 100. C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C GO TO 20 10 CONTINUE C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C PARAMETERS ARE INVALID. SET IFLAG = 1, AND TERMINATE C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C IFLAG = 1 RETURN 20 CONTINUE C C*************************************************************** C C **** FIRST, IN TOPBLK.... C C*************************************************************** C C *** APPLY NRWTOP COLUMN ELIMINATIONS WITH COLUMN C PIVOTING .... C C*************************************************************** C DO 110 I = 1, NRWTOP IPLUS1 = I+1 C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C DETERMINE COLUMN PIVOT AND PIVOT INDEX C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C IPVT = I COLMAX = DABS(TOPBLK(I,I)) DO 30 J = IPLUS1, NOVRLP TEMPIV = DABS(TOPBLK(I,J)) IF (TEMPIV.LE.COLMAX) GO TO 30 IPVT = J COLMAX = TEMPIV 30 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C TEST FOR SINGULARITY: C C IF SINGULAR THEN TERMINATE AT 1000; C ELSE CONTINUE. C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C IF (PIVMAX+COLMAX.EQ.PIVMAX) GO TO 410 PIVMAX = DMAX1(COLMAX,PIVMAX) C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C IF NECESSARY INTERCHANGE COLUMNS C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C PIVOT(I) = IPVT IF (IPVT.EQ.I) GO TO 60 DO 40 L = I, NRWTOP SWAP = TOPBLK(L,IPVT) TOPBLK(L,IPVT) = TOPBLK(L,I) TOPBLK(L,I) = SWAP 40 CONTINUE DO 50 L = 1, NRWBLK SWAP = ARRAY(L,IPVT,1) ARRAY(L,IPVT,1) = ARRAY(L,I,1) ARRAY(L,I,1) = SWAP 50 CONTINUE 60 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C COMPUTE MULTIPLIERS AND PERFORM COLUMN C ELIMINATION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C COLPIV = TOPBLK(I,I) DO 100 J = IPLUS1, NOVRLP COLMLT = TOPBLK(I,J)/COLPIV TOPBLK(I,J) = COLMLT IF (IPLUS1.GT.NRWTOP) GO TO 80 DO 70 L = IPLUS1, NRWTOP TOPBLK(L,J) = TOPBLK(L,J)-COLMLT*TOPBLK(L,I) 70 CONTINUE 80 CONTINUE DO 90 L = 1, NRWBLK ARRAY(L,J,1) = ARRAY(L,J,1)-COLMLT*ARRAY(L,I,1) 90 CONTINUE 100 CONTINUE 110 CONTINUE C C*************************************************************** C C **** IN EACH BLOCK ARRAY(,,K).... C C*************************************************************** C INCR = 0 DO 320 K = 1, NBLOKS KPLUS1 = K+1 C C ***************************************************** C C *** FIRST APPLY NRWBLK-NRWTOP ROW ELIMINATIONS WITH C ROW PIVOTING.... C C ***************************************************** C DO 180 J = NRWTP1, NRWBLK JPLUS1 = J+1 JMINN = J-NRWTOP C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C DETERMINE ROW PIVOT AND PIVOT INDEX C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C IPVT = JMINN ROWMAX = DABS(ARRAY(JMINN,J,K)) LOOP = JMINN+1 DO 120 I = LOOP, NRWBLK TEMPIV = DABS(ARRAY(I,J,K)) IF (TEMPIV.LE.ROWMAX) GO TO 120 IPVT = I ROWMAX = TEMPIV 120 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C TEST FOR SINGULARITY: C C IF SINGULAR THEN TERMINATE AT 1000; C ELSE CONTINUE. C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C IF (PIVMAX+ROWMAX.EQ.PIVMAX) GO TO 410 PIVMAX = DMAX1(ROWMAX,PIVMAX) C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C IF NECESSARY INTERCHANGE ROWS C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C INCRJ = INCR+J PIVOT(INCRJ) = INCR+IPVT+NRWTOP IF (IPVT.EQ.JMINN) GO TO 140 DO 130 L = J, NCLBLK SWAP = ARRAY(IPVT,L,K) ARRAY(IPVT,L,K) = ARRAY(JMINN,L,K) ARRAY(JMINN,L,K) = SWAP 130 CONTINUE 140 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C COMPUTE MULTIPLERS C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C ROWPIV = ARRAY(JMINN,J,K) DO 150 I = LOOP, NRWBLK ARRAY(I,J,K) = ARRAY(I,J,K)/ROWPIV 150 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C PERFORM ROW ELIMINATION WITH COLUMN INDEXING C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C DO 170 L = JPLUS1, NCLBLK ROWMLT = ARRAY(JMINN,L,K) DO 160 I = LOOP, NRWBLK ARRAY(I,L,K) = ARRAY(I,L,K)-ROWMLT*ARRAY(I,J,K) 160 CONTINUE 170 CONTINUE 180 CONTINUE C C ***************************************************** C C *** NOW APPLY NRWTOP COLUMN ELIMINATIONS WITH C COLUMN PIVOTING.... C C ***************************************************** C DO 310 I = NRWEL1, NRWBLK IPLUSN = I+NRWTOP IPLUS1 = I+1 C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C DETERMINE COLUMN PIVOT AND PIVOT INDEX C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C IPVT = IPLUSN COLMAX = DABS(ARRAY(I,IPVT,K)) LOOP = IPLUSN+1 DO 190 J = LOOP, NCLBLK TEMPIV = DABS(ARRAY(I,J,K)) IF (TEMPIV.LE.COLMAX) GO TO 190 IPVT = J COLMAX = TEMPIV 190 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C TEST FOR SINGULARITY: C C IF SINGULAR THEN TERMINATE AT 1000; C ELSE CONTINUE. C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C IF (PIVMAX+COLMAX.EQ.PIVMAX) GO TO 410 PIVMAX = DMAX1(COLMAX,PIVMAX) C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C IF NECESSARY INTERCHANGE COLUMNS C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C INCRN = INCR+IPLUSN PIVOT(INCRN) = INCR+IPVT IRWBLK = IPLUSN-NRWBLK IF (IPVT.EQ.IPLUSN) GO TO 240 DO 200 L = I, NRWBLK SWAP = ARRAY(L,IPVT,K) ARRAY(L,IPVT,K) = ARRAY(L,IPLUSN,K) ARRAY(L,IPLUSN,K) = SWAP 200 CONTINUE IPVBLK = IPVT-NRWBLK IF (K.EQ.NBLOKS) GO TO 220 DO 210 L = 1, NRWBLK SWAP = ARRAY(L,IPVBLK,KPLUS1) ARRAY(L,IPVBLK,KPLUS1) = ARRAY(L,IRWBLK,KPLUS1) ARRAY(L,IRWBLK,KPLUS1) = SWAP 210 CONTINUE GO TO 240 220 CONTINUE DO 230 L = 1, NRWBOT SWAP = BOTBLK(L,IPVBLK) BOTBLK(L,IPVBLK) = BOTBLK(L,IRWBLK) BOTBLK(L,IRWBLK) = SWAP 230 CONTINUE 240 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C COMPUTE MULTIPLIERS AND PERFORM COLUMN C ELIMINATION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C COLPIV = ARRAY(I,IPLUSN,K) DO 300 J = LOOP, NCLBLK COLMLT = ARRAY(I,J,K)/COLPIV ARRAY(I,J,K) = COLMLT IF (I.EQ.NRWBLK) GO TO 260 DO 250 L = IPLUS1, NRWBLK ARRAY(L,J,K) = ARRAY(L,J,K)-COLMLT*ARRAY(L,IPLUSN,K) 250 CONTINUE 260 CONTINUE JRWBLK = J-NRWBLK IF (K.EQ.NBLOKS) GO TO 280 DO 270 L = 1, NRWBLK ARRAY(L,JRWBLK,KPLUS1) = ARRAY(L,JRWBLK,KPLUS1)-COLMLT * *ARRAY(L,IRWBLK,KPLUS1) 270 CONTINUE GO TO 300 280 CONTINUE DO 290 L = 1, NRWBOT BOTBLK(L,JRWBLK) = BOTBLK(L,JRWBLK)-COLMLT*BOTBLK(L, * IRWBLK) 290 CONTINUE 300 CONTINUE 310 CONTINUE INCR = INCR+NRWBLK 320 CONTINUE C C*************************************************************** C C **** FINALLY, IN BOTBLK.... C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C *** APPLY NRWBOT ROW ELIMINATIONS WITH ROW C PIVOTING.... C C IF BOT HAS JUST ONE ROW GO TO 500 C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C IF (NRWBOT.EQ.1) GO TO 400 DO 390 J = NRWTP1, NVRLP0 JPLUS1 = J+1 JMINN = J-NRWTOP C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C DETERMINE ROW PIVOT AND PIVOT INDEX C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C IPVT = JMINN ROWMAX = DABS(BOTBLK(JMINN,J)) LOOP = JMINN+1 DO 330 I = LOOP, NRWBOT TEMPIV = DABS(BOTBLK(I,J)) IF (TEMPIV.LE.ROWMAX) GO TO 330 IPVT = I ROWMAX = TEMPIV 330 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C TEST FOR SINGULARITY: C C IF SINGULAR THEN TERMINATE AT 1000; C ELSE CONTINUE. C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C IF (PIVMAX+ROWMAX.EQ.PIVMAX) GO TO 410 PIVMAX = DMAX1(ROWMAX,PIVMAX) C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C IF NECESSARY INTERCHANGE ROWS C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C INCRJ = INCR+J PIVOT(INCRJ) = INCR+IPVT+NRWTOP IF (IPVT.EQ.JMINN) GO TO 350 DO 340 L = J, NOVRLP SWAP = BOTBLK(IPVT,L) BOTBLK(IPVT,L) = BOTBLK(JMINN,L) BOTBLK(JMINN,L) = SWAP 340 CONTINUE 350 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C COMPUTE MULTIPLIERS C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C ROWPIV = BOTBLK(JMINN,J) DO 360 I = LOOP, NRWBOT BOTBLK(I,J) = BOTBLK(I,J)/ROWPIV 360 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C PERFORM ROW ELIMINATION WITH COLUMN INDEXING C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C DO 380 L = JPLUS1, NOVRLP ROWMLT = BOTBLK(JMINN,L) DO 370 I = LOOP, NRWBOT BOTBLK(I,L) = BOTBLK(I,L)-ROWMLT*BOTBLK(I,J) 370 CONTINUE 380 CONTINUE 390 CONTINUE 400 CONTINUE C C*************************************************************** C C DONE PROVIDED THE LAST ELEMENT IS NOT ZERO C C*************************************************************** C IF (PIVMAX+DABS(BOTBLK(NRWBOT,NOVRLP)).NE.PIVMAX) RETURN C C*************************************************************** C C **** MATRIX IS SINGULAR - SET IFLAG = - 1. C TERMINATE AT 1000. C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C 410 CONTINUE IFLAG = -1 RETURN END SUBROUTINE CRSLVE (TOPBLK,NRWTOP,NOVRLP,ARRAY,NRWBLK,NCLBLK,NBLOKS * ,BOTBLK,NRWBOT,PIVOT,B,X) C C*************************************************************** C C C R S L V E SOLVES THE LINEAR SYSTEM C A*X = B C USING THE DECOMPOSITION ALREADY GENERATED IN C R D C M P. C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C ***** PARAMETERS ***** C C *** ON ENTRY ... C C TOPBLK - DOUBLE PRECISION(NRWTOP,NOVRLP) C OUTPUT FROM C R D C M P C C NOVRLP - INTEGER C THE NUMBER OF COLUMNS IN WHICH SUCC- C ESSIVE BLOCKS OVERLAP, WHERE C NOVRLP = NRWTOP + NRWBOT C C NRWTOP - INTEGER C NUMBER OF ROWS IN THE BLOCK TOPBLK C C ARRAY - DOUBLE PRECISION(NRWBLK,NCLBLK,NBLOKS) C OUTPUT FROM C R D C M P C C NRWBLK - INTEGER C NUMBER OF ROWS IN K-TH BLOCK C C NCLBLK - INTEGER C NUMBER OF COLUMNS IN K-TH BLOCK C C NBLOKS - INTEGER C NUMBER OF NRWBLK BY NCLBLK BLOCKS IN C THE MATRIX A C C BOTBLK - DOUBLE PRECISION(NRWBOT,NOVRLP) C OUTPUT FROM C R D C M P C C NRWBOT - INTEGER C NUMBER OF ROWS IN THE BLOCK BOTBLK C C PIVOT - INTEGER(N) C THE PIVOT VECTOR FROM C R D C M P C C B - DOUBLE PRECISION(N) C THE RIGHT HAND SIDE VECTOR C C X - DOUBLE PRECISION(N) C WORK SPACE C C *** ON RETURN ... C C X - DOUBLE PRECISION(N) C THE SOLUTION VECTOR C C*************************************************************** C IMPLICIT DOUBLE PRECISION(A-H,O-Z) INTEGER PIVOT(1) DIMENSION TOPBLK(NRWTOP,1),ARRAY(NRWBLK,NCLBLK,1),BOTBLK(NRWBOT,1) * ,B(1),X(1) C C*************************************************************** C C **** DEFINE THE CONSDTANTS USED THROUGHOUT **** C C*************************************************************** C NRWTP1 = NRWTOP+1 NRWBK1 = NRWBLK+1 NVRLP1 = NOVRLP+1 NRWTP0 = NRWTOP-1 NRWBT1 = NRWBOT+1 NROWEL = NRWBLK-NRWTOP NRWEL1 = NROWEL+1 NVRLP0 = NOVRLP-1 NBLKS1 = NBLOKS+1 NBKTOP = NRWBLK+NRWTOP C C*************************************************************** C C **** FORWARD RECURSION **** C C*************************************************************** C C *** FIRST, IN TOPBLK.... C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C FORWARD SOLUTION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C DO 30 J = 1, NRWTOP X(J) = B(J)/TOPBLK(J,J) IF (J.EQ.NRWTOP) GO TO 20 XJ = -X(J) LOOP = J+1 DO 10 I = LOOP, NRWTOP B(I) = B(I)+TOPBLK(I,J)*XJ 10 CONTINUE 20 CONTINUE 30 CONTINUE C C ******************************************************** C C *** IN EACH BLOCK ARRAY(,,K).... C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C INCR = 0 DO 120 K = 1, NBLOKS INCRTP = INCR+NRWTOP C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C FORWARD MODIFICATION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C DO 50 J = 1, NRWTOP INCRJ = INCR+J XINCRJ = -X(INCRJ) DO 40 I = 1, NRWBLK INCRI = INCRTP+I B(INCRI) = B(INCRI)+ARRAY(I,J,K)*XINCRJ 40 CONTINUE 50 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C FORWARD ELIMINATION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C DO 80 J = NRWTP1, NRWBLK INCRJ = INCR+J JPIVOT = PIVOT(INCRJ) IF (JPIVOT.EQ.INCRJ) GO TO 60 SWAP = B(INCRJ) B(INCRJ) = B(JPIVOT) B(JPIVOT) = SWAP 60 CONTINUE BINCRJ = -B(INCRJ) LOOP = J-NRWTP0 DO 70 I = LOOP, NRWBLK INCRI = INCRTP+I B(INCRI) = B(INCRI)+ARRAY(I,J,K)*BINCRJ 70 CONTINUE 80 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C FORWARD SOLUTION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C DO 110 J = NRWBK1, NBKTOP INCRJ = INCR+J JRWTOP = J-NRWTOP X(INCRJ) = B(INCRJ)/ARRAY(JRWTOP,J,K) IF (J.EQ.NBKTOP) GO TO 100 XINCRJ = -X(INCRJ) LOOP = J-NRWTP0 DO 90 I = LOOP, NRWBLK INCRI = INCRTP+I B(INCRI) = B(INCRI)+ARRAY(I,J,K)*XINCRJ 90 CONTINUE 100 CONTINUE 110 CONTINUE INCR = INCR+NRWBLK 120 CONTINUE C C ******************************************************** C C *** FINALLY, IN BOTBLK.... C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C FORWARD MODIFICATION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C INCRTP = INCR+NRWTOP DO 140 J = 1, NRWTOP INCRJ = INCR+J XINCRJ = -X(INCRJ) DO 130 I = 1, NRWBOT INCRI = INCRTP+I B(INCRI) = B(INCRI)+BOTBLK(I,J)*XINCRJ 130 CONTINUE 140 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C FORWARD ELIMINATION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C IF (NRWBOT.EQ.1) GO TO 180 DO 170 J = NRWTP1, NVRLP0 INCRJ = INCR+J JPIVOT = PIVOT(INCRJ) IF (JPIVOT.EQ.INCRJ) GO TO 150 SWAP = B(INCRJ) B(INCRJ) = B(JPIVOT) B(JPIVOT) = SWAP 150 CONTINUE BINCRJ = -B(INCRJ) LOOP = J-NRWTP0 DO 160 I = LOOP, NRWBOT INCRI = INCRTP+I B(INCRI) = B(INCRI)+BOTBLK(I,J)*BINCRJ 160 CONTINUE 170 CONTINUE 180 CONTINUE C C*************************************************************** C C **** BACKWARD RECURSION **** C C*************************************************************** C C *** FIRST IN BOTBLK.... C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C BACKWARD SOLUTION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C DO 210 LL = 1, NRWBOT J = NVRLP1-LL INCRJ = INCR+J NRWBTL = NRWBT1-LL X(INCRJ) = B(INCRJ)/BOTBLK(NRWBTL,J) IF (LL.EQ.NRWBOT) GO TO 200 XINCRJ = -X(INCRJ) LOOP = NRWBOT-LL DO 190 I = 1, LOOP INCRI = INCRTP+I B(INCRI) = B(INCRI)+BOTBLK(I,J)*XINCRJ 190 CONTINUE 200 CONTINUE 210 CONTINUE C C ******************************************************** C C *** THEN IN EACH BLOCK ARRAY(,,K).... C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C DO 300 L = 1, NBLOKS C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C BACKWARD ELIMINATION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C K = NBLKS1-L INCR = INCR-NRWBLK DO 240 L1 = NRWEL1, NRWBLK I = NRWBLK+NRWEL1-L1 IPLUSN = I+NRWTOP LOOP = IPLUSN+1 INCRN = INCR+IPLUSN DOTPRD = X(INCRN) DO 220 J = LOOP, NCLBLK INCRJ = INCR+J DOTPRD = DOTPRD-ARRAY(I,J,K)*X(INCRJ) 220 CONTINUE X(INCRN) = DOTPRD IPVTN = PIVOT(INCRN) IF (INCRN.EQ.IPVTN) GO TO 230 SWAP = X(INCRN) X(INCRN) = X(IPVTN) X(IPVTN) = SWAP 230 CONTINUE 240 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C BACKWARD MODIFICATION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C INCRTP = INCR+NRWTOP DO 260 J = NRWBK1, NCLBLK INCRJ = INCR+J XINCRJ = -X(INCRJ) DO 250 I = 1, NROWEL INCRI = INCRTP+I B(INCRI) = B(INCRI)+ARRAY(I,J,K)*XINCRJ 250 CONTINUE 260 CONTINUE C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C BACKWARD SOLUTION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C DO 290 LL = 1, NROWEL J = NRWBK1-LL INCRJ = INCR+J NRWELL = NRWEL1-LL X(INCRJ) = B(INCRJ)/ARRAY(NRWELL,J,K) IF (LL.EQ.NROWEL) GO TO 280 XINCRJ = -X(INCRJ) LOOP = NROWEL-LL DO 270 I = 1, LOOP INCRI = INCRTP+I B(INCRI) = B(INCRI)+ARRAY(I,J,K)*XINCRJ 270 CONTINUE 280 CONTINUE 290 CONTINUE 300 CONTINUE C C ******************************************************** C C *** IN TOPBLK FINISH WITH.... C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C BACKWARD ELIMINATION C C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C DO 330 L = 1, NRWTOP I = NRWTP1-L LOOP = I+1 DOTPRD = X(I) DO 310 J = LOOP, NOVRLP DOTPRD = DOTPRD-TOPBLK(I,J)*X(J) 310 CONTINUE X(I) = DOTPRD IPVTI = PIVOT(I) IF (I.EQ.IPVTI) GO TO 320 SWAP = X(I) X(I) = X(IPVTI) X(IPVTI) = SWAP 320 CONTINUE 330 CONTINUE RETURN END subroutine lufac(n, ndim, a, ip, ier) implicit double precision (a-h,o-z) dimension a(ndim,n), ip(n) intrinsic abs * blas: daxpy, dscal, dswap. idamax parameter ( zero = 0.0d+0, one = 1.0d+0 ) * The subroutine lufac is a very simple code to compute the * LU decomposition (with partial pivoting) of the n by n matrix a. * The LU factors are overwritten on a. The integer array ip * reflects the pairwise interchanges performed. note that ip(k) * therefore does not give the index in the original array of * the k-th pivot. * On exit, the error flag ier is zero when no zero pivots are * encountered. Otherwise, ier is equal to the index of the * step at which a zero pivot occurred. ier = 0 ip(n) = 0 * Begin loop over columns 1 through n-1. k is the current * column index. do 100 k = 1, n-1 * Find the row index ipiv of the element of largest magnitude in * column k. ipiv = k-1 + idamax(n-k+1, a(k,k), 1) piv = a(ipiv,k) if (piv .eq. zero) then ier = k return endif ip(k) = ipiv * Perform interchanges if necessary. if (ipiv .ne. k) then call dswap(n-k+1, a(ipiv,k), ndim, a(k,k), ndim) endif * Save the (negative) multipliers in the subdiagonal elements of * column k. call dscal(n-k, (-one/piv), a(k+1,k), 1) * Update the remaining matrix. Note that a(i,k) now contains * the negative multipliers. do 50 j = k+1, n call daxpy(n-k, a(k,j), a(k+1,k), 1, a(k+1,j), 1) 50 continue * End of loop over columns. 100 continue if (a(n,n).eq.zero) ier = n return end subroutine lusol (n, ndim, a, ip, b, x) implicit double precision (a-h, o-z) dimension a(ndim,n), ip(n), b(n), x(n) * blas: daxpy, dcopy * The subroutine lusol is a simple-minded routine to solve a * linear system whose LU factors have been computed by lufac. * On entry, the matrix a should contain the LU factors, and * ip should contain the interchange array constructed by lufac. * Copy the right-hand side b into x. call dcopy (n, b, 1, x, 1) * Forward solution with l (unit lower-triangular factor), which * is stored in the strict lower triangle of a. do 20 k = 1, n-1 ipiv = ip(k) if (ipiv .ne. k) then tem = x(ipiv) x(ipiv) = x(k) x(k) = tem endif call daxpy ( n-k, x(k), a(k+1,k), 1, x(k+1), 1 ) 20 continue * Backward solution with u (upper-triangular factor), which is stored * in the upper triangle of a. do 40 kb = n, 1, -1 x(kb) = x(kb)/a(kb,kb) call daxpy(kb-1, (-x(kb)), a(1,kb), 1, x(1), 1) 40 continue return end subroutine dcopy ( n, x, incx, y, incy ) implicit double precision (a-h,o-z) integer n, incx, incy dimension x( * ), y( * ) c dcopy performs the operation c c y := x c c nag fortran 77 version of the blas routine dcopy . c nag fortran 77 o( n ) basic linear algebra routine. c c -- written on 26-november-1982. c sven hammarling, nag central office. integer i , ix , iy if( n.lt.1 )return if( ( incx.eq.incy ).and.( incy.gt.0 ) )then do 10, iy = 1, 1 + ( n - 1 )*incy, incy y( iy ) = x( iy ) 10 continue else if( incx.ge.0 )then ix = 1 else ix = 1 - ( n - 1 )*incx end if if( incy.gt.0 )then do 20, iy = 1, 1 + ( n - 1 )*incy, incy y( iy ) = x( ix ) ix = ix + incx 20 continue else iy = 1 - ( n - 1 )*incy do 30, i = 1, n y( iy ) = x( ix ) iy = iy + incy ix = ix + incx 30 continue end if end if return * end of dcopy . end subroutine daxpy ( n, alpha, x, incx, y, incy ) implicit double precision (a-h,o-z) integer n, incx, incy dimension x( * ), y( * ) c daxpy performs the operation c c y := alpha*x + y c c c modified nag fortran 77 version of the blas routine daxpy . c c -- written on 3-september-1982. c sven hammarling, nag central office. integer i , ix , iy parameter ( zero = 0.0+0 ) if( n .lt.1 )return if( alpha.eq.zero )return if( ( incx.eq.incy ).and.( incx.gt.0 ) )then do 10, ix = 1, 1 + ( n - 1 )*incx, incx y( ix ) = alpha*x( ix ) + y( ix ) 10 continue else if( incy.ge.0 )then iy = 1 else iy = 1 - ( n - 1 )*incy end if if( incx.gt.0 )then do 20, ix = 1, 1 + ( n - 1 )*incx, incx y( iy ) = alpha*x( ix ) + y( iy ) iy = iy + incy 20 continue else ix = 1 - ( n - 1 )*incx do 30, i = 1, n y( iy ) = alpha*x( ix ) + y( iy ) ix = ix + incx iy = iy + incy 30 continue end if end if return * end of daxpy . end double precision function ddot ( n, x, incx, y, incy ) implicit double precision (a-h,o-z) integer n, incx, incy dimension x( * ), y( * ) c ddot returns the value c c ddot = x'y c c c modified nag fortran 77 version of the blas routine ddot . c c -- written on 21-september-1982. c sven hammarling, nag central office. integer i , ix , iy parameter ( zero = 0.0d+0 ) sum = zero if( n.ge.1 )then if( ( incx.eq.incy ).and.( incx.gt.0 ) )then do 10, ix = 1, 1 + ( n - 1 )*incx, incx sum = sum + x( ix )*y( ix ) 10 continue else if( incy.ge.0 )then iy = 1 else iy = 1 - ( n - 1 )*incy end if if( incx.gt.0 )then do 20, ix = 1, 1 + ( n - 1 )*incx, incx sum = sum + x( ix )*y( iy ) iy = iy + incy 20 continue else ix = 1 - ( n - 1 )*incx do 30, i = 1, n sum = sum + x( ix )*y( iy ) ix = ix + incx iy = iy + incy 30 continue end if end if end if ddot = sum return * end of ddot . end subroutine dscal ( n, alpha, x, incx ) implicit double precision (a-h,o-z) integer n, incx dimension x( * ) c dscal performs the operation c c x := alpha*x c c c modified nag fortran 77 version of the blas routine dscal . c c -- written on 26-november-1982. c sven hammarling, nag central office. integer ix parameter ( one = 1.0d+0, zero = 0.0d+0 ) if( n.ge.1 )then if( alpha.eq.zero )then do 10, ix = 1, 1 + ( n - 1 )*incx, incx x( ix ) = zero 10 continue else if( alpha.eq.( -one ) )then do 20, ix = 1, 1 + ( n - 1 )*incx, incx x( ix ) = -x( ix ) 20 continue else if( alpha.ne.one )then do 30, ix = 1, 1 + ( n - 1 )*incx, incx x( ix ) = alpha*x( ix ) 30 continue end if end if return * end of dscal . end subroutine dswap ( n, x, incx, y, incy ) implicit double precision (a-h,o-z) integer n, incx, incy dimension x( * ), y( * ) c dswap performs the operations c c temp := x, x := y, y := temp. c c c modified nag fortran 77 version of the blas routine dswap . c c -- written on 26-november-1982. c sven hammarling, nag central office. integer i , ix , iy if( n.lt.1 )return if( ( incx.eq.incy ).and.( incy.gt.0 ) )then do 10, iy = 1, 1 + ( n - 1 )*incy, incy temp = x( iy ) x( iy ) = y( iy ) y( iy ) = temp 10 continue else if( incx.ge.0 )then ix = 1 else ix = 1 - ( n - 1 )*incx end if if( incy.gt.0 )then do 20, iy = 1, 1 + ( n - 1 )*incy, incy temp = x( ix ) x( ix ) = y( iy ) y( iy ) = temp ix = ix + incx 20 continue else iy = 1 - ( n - 1 )*incy do 30, i = 1, n temp = x( ix ) x( ix ) = y( iy ) y( iy ) = temp iy = iy + incy ix = ix + incx 30 continue end if end if return * end of dswap . end integer function idamax( n, x, incx ) implicit double precision (a-h,o-z) integer n, incx dimension x( * ) c idamax returns the smallest value of i such that c c abs( x( i ) ) = max( abs( x( j ) ) ) c j c c nag fortran 77 version of the blas routine idamax. c nag fortran 77 o( n ) basic linear algebra routine. c c -- written on 31-may-1983. c sven hammarling, nag central office. intrinsic abs integer i , imax , ix if( n.lt.1 )then idamax = 0 return end if imax = 1 if( n.gt.1 )then xmax = abs( x( 1 ) ) ix = 1 do 10, i = 2, n ix = ix + incx if( xmax.lt.abs( x( ix ) ) )then xmax = abs( x( ix ) ) imax = i end if 10 continue end if idamax = imax return * end of idamax. end subroutine dload ( n, const, x, incx ) implicit double precision (a-h,o-z) dimension x(*) c c dload performs the operation c c x = const*e, e' = ( 1 1 ... 1 ). c c c nag fortran 77 o( n ) basic linear algebra routine. c c -- written on 22-september-1983. c sven hammarling, nag central office. c parameter ( zero = 0.0d+0 ) if( n.lt.1 )return if( const.ne.zero )then do 10, ix = 1, 1 + ( n - 1 )*incx, incx x( ix ) = const 10 continue else do 20, ix = 1, 1 + ( n - 1 )*incx, incx x( ix ) = zero 20 continue end if return * end of dload . end subroutine maxpy ( nrow, ncol, alpha, xmat, nrowy, ymat ) implicit double precision (a-h,o-z) dimension xmat(nrow, ncol), ymat(nrowy, ncol) * Subroutine maxpy takes as input the scalar alpha and two matrices, * xmat and ymat. xmat has declared row dimension nrow, and * ymat has declared row dimension nrowy, but both are * conceptually nrow by ncol. * On output, (new ymat) is alpha*xmat+ (old ymat), by analogy * with the vector blas routine saxpy. do 100 j = 1, ncol do 100 i = 1, nrow ymat(i,j) = ymat(i,j) + alpha*xmat(i,j) 100 continue return end subroutine matcop( nrow1, nrow2, nrow, ncol, xmat1, xmat2 ) implicit double precision (a-h,o-z) dimension xmat1(nrow1, ncol), xmat2(nrow2, ncol) * Given 2 matrices xmat1 and xmat2, where xmat1 has declared * row dimension nrow1, xmat2 has declared row dimension nrow2, * and both have column dimension ncol, the routine matcop copies * rows 1 through nrow, and columns 1 through ncol from xmat1 into * xmat2. if (nrow .le. 0 .or. ncol .le. 0) return do 100 j = 1, ncol do 100 i = 1, nrow xmat2(i,j) = xmat1(i,j) 100 continue return end subroutine mtload( nrow, ncol, const, nrowx, xmat ) implicit double precision (a-h,o-z) dimension xmat(nrowx, ncol) * mtload sets elements 1 through nrow, 1 through ncol, of the * matrix xmat (whose declared row dimension is nrowx) to the * scalar value const. if (nrow .le. 0 .or. ncol .le. 0) return do 100 j = 1, ncol do 100 i = 1, nrow xmat(i,j) = const 100 continue return end subroutine mssq ( nrow, ncol, xmat, scale, sumsq ) implicit double precision (a-h,o-z) dimension xmat(nrow, *) * Given the nrow by ncol matrix xmat, mssq returns values * scale and sumsq such that * (scale**2) * sumsq = sum of squares of xmat(i,j), * where scale = max abs(xmat(i,j)). * mssq is a stripped-down matrix version of the blas routine sssq. intrinsic abs parameter ( one = 1.0d+0, zero = 0.0d+0 ) scale = zero sumsq = one if( nrow.ge.1 .and. ncol .ge. 1) then do 10 i = 1, nrow do 10 j = 1, ncol if( xmat(i,j) .ne. zero )then absxij = abs(xmat(i,j)) if( scale .lt. absxij ) then sumsq = one + sumsq* (scale/absxij)**2 scale = absxij else sumsq = sumsq + (absxij/scale)**2 end if end if 10 continue end if return end subroutine dssq ( n, x, incx, scale, sumsq ) implicit double precision (a-h,o-z) integer n, incx dimension x( * ) * Given the n-vector x, dssq returns values scale and sumsq such that * (scale**2) * sumsq = sum of squares of x(i), * where scale = max abs(x(i)). intrinsic abs parameter ( one = 1.0d+0, zero = 0.0d+0 ) scale = zero sumsq = one if( n.ge.1 )then do 10, ix = 1, 1 + ( n - 1 )*incx, incx if( x( ix ).ne.zero )then absxi = abs( x( ix ) ) if( scale.lt.absxi )then sumsq = one + sumsq*( scale/absxi )**2 scale = absxi else sumsq = sumsq + ( absxi/scale )**2 end if end if 10 continue end if return * end of dssq . end subroutine bvpsol(ncomp, nmsh, nlbc, aleft, aright, * nfxpnt, fixpnt, * ntol, ltol, tol, nmax, linear, giveu, givmsh, * xx, nudim, u, defexp, defimp, def, delu, rhs, fval, * topblk, botblk, ajac, bhold, chold, ipvblk, ipivlu, * uint, ftmp, tmprhs, dftmp1, dftmp2, dgtm, * utrial, rhstri, xmerit, xxold, uold, usave, * tmp, dsq, dexr, ratdc, rerr, * etest6, etest8, ermx, ihcomp, irefin, * def6, def8, fsub, dfsub, gsub, dgsub, iflbvp) implicit double precision (a-h,o-z) dimension fixpnt(*), ltol(ntol), tol(ntol) dimension xx(*), u(nudim, *) dimension defexp(ncomp,*), defimp(ncomp,*), def(ncomp,*) dimension delu(ncomp, *), rhs(*), fval(ncomp,*) dimension topblk(nlbc,*), botblk(ncomp-nlbc,*) dimension ajac(ncomp, 2*ncomp, *) dimension bhold(ncomp, ncomp, *), chold(ncomp, ncomp, *) dimension ipivlu(*), ipvblk(*) dimension uint(ncomp), ftmp(ncomp) dimension dgtm(ncomp), tmprhs(*) dimension dftmp1(ncomp, ncomp), dftmp2(ncomp, ncomp) dimension utrial(ncomp,*), rhstri(*) dimension xmerit(ncomp, *) dimension xxold(*), uold(ncomp,*), usave(ncomp,*) dimension tmp(ncomp,8) dimension dsq(ncomp,ncomp), dexr(ncomp) dimension ratdc(*), rerr(ncomp,*) dimension etest6(*), etest8(*), ermx(*) dimension ihcomp(*), irefin(*) dimension def6(ncomp,*), def8(ncomp,*) logical linear, giveu, givmsh, double external fsub, dfsub, gsub, dgsub common/mchprs/flmin, flmax, epsmch logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 intrinsic max logical smooth, succes, strctr, trst6, reaft6 logical onto6, onto8, ludone, rhsgiv, maxmsh logical first4, first8 logical mchset save mchset parameter (zero = 0.0d+0, one = 1.0d+0) parameter (third = 0.33d+0, fourth = 0.25d+0) parameter (quan6 = 0.1d+0 ) * blas: dload * double precision d1mach data mchset/.true./ data fxfct/10.0d+0/ data maxmsh/.false./ if (mchset) then flmin = d1mach(1) flmax = d1mach(2) epsmch = d1mach(3) if (pdebug) write(6,901) epsmch mchset = .false. endif * The routine stcons calculates integration constants stored in * labeled common consts. call stcons * Set up arrays for the error tests. if (.not. linear) then call dload(ntol, one, etest6, 1) else do 10 i = 1, ntol etest6(i) = one/max(quan6, tol(i)**third) 10 continue endif nmold = 1 smooth = .false. strctr = .false. trst6 = .true. reaft6 = .false. numbig = 0 nummed = 0 first4 = .true. first8 = .true. * * If givmsh is .true., the initial number of mesh points must be * provided by the user in nmsh, and the mesh points must be * contained in the array xx (of dimension nmsh). * Otherwise, nmsh is set to its default value, and a * uniform initial mesh is created. if (.not. giveu .and. .not. givmsh) then nmsh = nminit if (nmsh .lt. nfxpnt+2) nmsh = nfxpnt + 2 call unimsh(nmsh, aleft, aright, nfxpnt, fixpnt, xx) endif if (pdebug) then write(6,902) call sprt(nmsh, xx) endif if (.not. giveu) call initu(ncomp, nmsh, xx, nudim, u) ***** top of logic for 4th order solution **** 400 continue if (iprint .eq. 1) write(6,903) nmsh * Set the def (deferred correction) array to zero. call mtload(ncomp, nmsh-1, zero, ncomp, def) iorder = 4 * The routine fneval calls fsub at the mesh xx and the * solution u, and saves the values in the array fval. call fneval(ncomp, nmsh, xx, nudim, u, fval, fsub) * Try to compute a 4th order solution by solving a system of nonlinear * equations. if (linear) then ludone = .false. call lineq( ncomp, nmsh, nlbc, * ludone, xx, nudim, u, def, * delu, rhs, fval, * uint, ftmp, dftmp1, dftmp2, dgtm, tmprhs, * ajac, topblk, botblk, bhold, chold, ipvblk, * fsub, dfsub, gsub, dgsub, iflnwt) * Call fneval to evaluate the fval array at the new solution u. * (Such a call is not necessary for the nonlinear case because * fval is called within newteq for the new u.) call fneval(ncomp, nmsh, xx, nudim, u, fval, fsub) else rhsgiv = .false. call newteq(ncomp, nmsh, nlbc, * rhsgiv, ntol, ltol, tol, * xx, nudim, u, def, * delu, rhs, fval, * utrial, rhstri, * uint, ftmp, dftmp1, dftmp2, dgtm, tmprhs, xmerit, * ajac, topblk, botblk, bhold, chold, ipvblk, * fsub, dfsub, gsub, dgsub, itnwt, iflnwt) endif if (iflnwt .eq. 0) then call conv4( ncomp, nmsh, ntol, ltol, tol, linear, nmax, * xx, nudim, u, defexp, defimp, def, fval, * tmp, bhold, chold, dsq, dexr, usave, * ratdc, rerr, ipivlu, nmold, xxold, * smooth, reaft6, onto6, strctr, trst6, double, * fsub, maxmsh, succes, first4) if (pdebug .and. .not. onto6) write (6,904) else succes = .false. onto6 = .false. call fail4( ncomp, nmsh, nlbc, ntol, ltol, * xx, nudim, u, rhs, linear, nmax, * nmold, xxold, uold, ratdc, * iorder, iflnwt, itnwt, double, maxmsh, * numbig, nummed) endif if (succes) then iflbvp = 0 return elseif (maxmsh) then go to 900 elseif (.not. onto6) then go to 400 endif * To reach here, onto6 must be .true. **** logic for 6th order **** if (iprint .eq. 1) write(6,905) * Save the 4th order solution on this mesh in uold. call matcop(nudim, ncomp, ncomp, nmsh, u, uold) iorder = 6 if (linear) then call lineq( ncomp, nmsh, nlbc, * ludone, xx, nudim, u, def, * delu, rhs, fval, * uint, ftmp, dftmp1, dftmp2, dgtm, tmprhs, * ajac, topblk, botblk, chold, bhold, ipvblk, * fsub, dfsub, gsub, dgsub, iflnwt) else call fixjac(ncomp, nmsh, nlbc, * iorder, ntol, ltol, tol, * xx, nudim, u, def, def, delu, * rhs, fval, utrial, rhstri, * rnsq, uint, ftmp, tmprhs, * ajac, topblk, botblk, ipvblk, * fsub, gsub, iflnwt) * If the fixed Jacobian iterations fail but rnsq is small, * try a Newton procedure. Set rhsgiv to indicate that * the right-hand side and fval have already been evaluated * at the given u. if (iflnwt .eq. -3 .and. rnsq .lt. fxfct*epsmch) then rhsgiv = .true. call newteq(ncomp, nmsh, nlbc, * rhsgiv, ntol, ltol, tol, * xx, nudim, u, def, * delu, rhs, fval, * utrial, rhstri, * uint, ftmp, dftmp1, dftmp2, dgtm, tmprhs, xmerit, * ajac, topblk, botblk, bhold, chold, ipvblk, * fsub, dfsub, gsub, dgsub, iter, iflnwt) endif endif if (iflnwt .eq. 0) then call conv6(ncomp, nmsh, ntol, ltol, tol, * nudim, u, uold, etest6, err6, * trst6, onto8, reaft6, succes) else onto8 = .false. call fail6( ncomp, nmsh, nlbc, ntol, ltol, tol, * nfxpnt, fixpnt, iorder, nmax, * xx, nudim, u, rhs, usave, xxold, uold, nmold, * ihcomp, irefin, * rerr, ermx, ratdc, * reaft6, double, succes, maxmsh, * numbig, nummed) endif if (succes) then iflbvp = 0 return elseif (maxmsh) then go to 900 elseif (.not. onto8) then go to 400 endif ***** logic for trying to calculate 8th order solution ***** if (iprint .eq. 1) write(6,906) call matcop(nudim, ncomp, ncomp, nmsh, u, uold) * Save the old deferred correction vector def in def6. call matcop(ncomp, ncomp, ncomp, nmsh-1, def, def6) * For linear problems, calculate the fval array for the * new solution u. if (linear) call fneval(ncomp, nmsh, xx, nudim, u, fval, fsub) * Calculate 8th order deferred corrections (the array def8). call df8cal (ncomp, nmsh, xx, nudim, u, fval, def8, * tmp, fsub) * For linear problems, the def array is the def8 array. * For nonlinear problems, add the def8 array to the * already-calculated def array. if (linear) then call matcop(ncomp, ncomp, ncomp, nmsh-1, def8, def) else call maxpy(ncomp, nmsh-1, one, def8, ncomp, def) endif iorder = 8 if (linear) then call lineq( ncomp, nmsh, nlbc, * ludone, xx, nudim, u, def, * delu, rhs, fval, * uint, ftmp, dftmp1, dftmp2, dgtm, tmprhs, * ajac, topblk, botblk, chold, bhold, ipvblk, * fsub, dfsub, gsub, dgsub, iflnwt) else call fixjac(ncomp, nmsh, nlbc, * iorder, ntol, ltol, tol, * xx, nudim, u, def, def8, delu, * rhs, fval, utrial, rhstri, * rnsq, uint, ftmp, tmprhs, * ajac, topblk, botblk, ipvblk, * fsub, gsub, iflnwt) * If the fixed Jacobian iterations fail but rnsq is small, * try a Newton procedure. Set rhsgiv to indicate that * the right-hand side and fval have already been evaluated * at the given u. if (iflnwt .eq. -3 .and. rnsq .lt. fxfct*epsmch) then rhsgiv = .true. call newteq(ncomp, nmsh, nlbc, * rhsgiv, ntol, ltol, tol, * xx, nudim, u, def, * delu, rhs, fval, * utrial, rhstri, * uint, ftmp, dftmp1, dftmp2, dgtm, tmprhs, xmerit, * ajac, topblk, botblk, bhold, chold, ipvblk, * fsub, dfsub, gsub, dgsub, iter, iflnwt) endif endif if (iflnwt .eq. 0) then call conv8( ncomp, nmsh, ntol, ltol, tol, * nfxpnt, fixpnt, linear, nmax, * xx, nudim, u, def, def6, def8, uold, * ihcomp, irefin, ermx, err6, * etest8, strctr, * double, nmold, xxold, maxmsh, succes, first8) else succes = .false. call fail8(ncomp, nmsh, nfxpnt, fixpnt, nmax, * ntol, ltol, tol, nmold, * xx, nudim, u, def6, xxold, uold, * ihcomp, irefin, ermx, double, maxmsh) endif if (maxmsh) then go to 900 elseif (.not. succes) then go to 400 endif * Successful termination. iflbvp = 0 return 900 continue * Error exit---too many mesh points. iflbvp = 1 return 901 format(1h ,'epsmch',1pe10.3) 902 format(1h ,'initial mesh') 903 format(1h ,'start 4th order, nmsh',i5) 904 format(1h ,'do not go on to 6th') 905 format(1h ,'start 6th order') 906 format(1h ,'start 8th order') end subroutine initu(ncomp, nmsh, xx, nudim, u) implicit double precision (a-h,o-z) dimension xx(*), u(nudim, *) logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 * This routine must be provided to reset u after re-meshing * for linear problems or for nonlinear problems * when interpolation of the old solution is not used. * This version sets all elements of u to the constant uval0. if (iprint .ne. -1) write(6,99) uval0 99 format(1h ,'initu, uval0',1pd15.5) call mtload(ncomp, nmsh, uval0, nudim, u) return end block data * This block data routine initializes nminit (the initial number * of mesh points), pdebug (a logical variable indicating whether * debug printout is desired), and uval0 (the initial value for the trial * solution) to their default values. double precision uval0 logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 data nminit/7/ data pdebug/.false./ data iprint/0/ data uval0/0.0d+0/ end subroutine conv4( ncomp, nmsh, ntol, ltol, tol, linear, nmax, * xx, nudim, u, defexp, defimp, def, fval, * tmp, bhold, chold, dsq, dexr, usave, * ratdc, rerr, ipivot, nmold, xxold, * smooth, reaft6, onto6, strctr, trst6, double, * fsub, maxmsh, succes, first4) implicit double precision (a-h,o-z) dimension ltol(ntol), ipivot(*) dimension xx(*), u(nudim,*), tol(ntol) dimension defexp(ncomp,*), defimp(ncomp,*), def(ncomp,*) dimension fval(ncomp,*), tmp(ncomp,4) dimension bhold(ncomp,ncomp,*), chold(ncomp, ncomp,*) dimension dsq(ncomp,ncomp), dexr(ncomp), usave(ncomp,*) dimension xxold(*) dimension ratdc(*), rerr(ncomp,*) logical linear, smooth, reaft6, onto6, strctr, trst6 logical double, succes, maxmsh, first4 external fsub logical callrt, oscchk, reposs, savedu logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 common/mchprs/flmin, flmax, epsmch parameter (hundth = 1.0d+5, rerfct = 1.5d+0) parameter (power = 1.0d+0/6.0d+0, one = 1.0d+0) parameter (zero = 0.0d+0, huge = 1.0d+30) intrinsic abs, max save dfold, oldrt1, savedu, reposs logical adjrer * The Newton iteration converged for a 4th order solution. if (iprint .eq. 1) write(6,901) if (first4) then dfold = zero oldrt1 = huge savedu = .false. reposs = .false. first4 = .false. endif succes = .false. maxmsh = .false. * Compute the explicit deferred correction array defexp. * The parameter fval is an ncomp by nmsh array, calculated * by a previous call to fneval for this mesh and solution. call dfexcl( ncomp, nmsh, xx, nudim, u, defexp, fval, * tmp, fsub ) call matcop(ncomp, ncomp, ncomp, nmsh-1, defexp, def) * If the problem has been declared as smooth, or we might wish * to perform Richardson extrapolation after trying to calculate a * 6th order solution, just go on to the 6th order logic (don't * bother to calculate implicit deferred corrections). if ( smooth .or. reaft6) then if (smooth .and. pdebug) write(6,902) if (reaft6 .and. pdebug) write(6,903) onto6 = .true. return endif * Compute the cheap implicit deferred correction array defimp. * The array chold must be unchanged from a call to jaccal * for this mesh and solution. * The temporary arrays dsq and dexr are calculated inside dfimcl. call dfimcl( ncomp, nmsh, defexp, chold, dsq, dexr, * ipivot, defimp) * Call dccal to calculate: dfexmx, the maximum-magnitude element * of defexp in components for which tolerances are specified; * incmp, inmsh, and intol, the indices of the component, * mesh interval, and tolerance of dfexmx; derivm, the * maximum-magnitude element of fval(incmp,*) for all mesh * points; dfimmx, the maximum-magnitude element of defimp in * component incmp; the ratios rat1 and rat2; and the array * ratdc (used in osc). dfctol = hundth*epsmch call dccal( ncomp, nmsh, ntol, ltol, * defexp, defimp, dfctol, fval, * ratdc, dfexmx, incmp, inmsh, intol, * derivm, dfimmx, rat1, rat2) * decid4 sets logical flags that determine the next step of the * algorithm. call decid4(linear, rat1, rat2, dfexmx, dfimmx, * derivm, dfold, tol(intol), oldrt1, * onto6, smooth, callrt, strctr, oscchk, double, reposs) if (pdebug) then if (smooth) write(6,904) if (callrt) write(6,905) if (oscchk) write(6,906) if (strctr) write(6,907) if (reposs) write(6,908) if (savedu) write(6,909) if (onto6) write(6,910) write(6,911) rat1, oldrt1 endif oldrt1 = rat1 dfold = dfexmx if (callrt) then * ratcor calculates a more expensive implicit deferred correction. * The matrix bhold must be unchanged from the last call to jaccal. * If callrt is true, onto6 is always true also. call ratcor( ncomp, nmsh, xx, defimp, bhold, def) elseif (linear) then if (oscchk) then call osc (ncomp, nmsh, dfexmx, incmp, * defexp, ratdc, double, inmsh, onto6, trst6, * smooth) elseif (reposs) then * If reposs (`Richardson extrapolation possible') is true * for two successive 4th order solutions, a special termination * test may be used based on Richardson extrapolation. * If reposs is true for the first time, savedu will * be false; savedu can be true only when reposs is true for a * second consecutive mesh (a doubled version of the first). if (savedu) then * The flag savedu is .true. when the immediately preceding * converged 4th order solution was saved in the array usave, * and the mesh was then doubled. * In this case, the routine rerrvl is called to compute a * Richardson extrapolation (RE) error estimate remax. * The rerr array does not need to be adjusted, so adjrer is false. adjrer = .false. call rerrvl( ncomp, nmsh, nudim, u, usave, ntol, * ltol, rerr, remax, itlmx, adjrer ) if (remax .lt. rerfct*tol(itlmx)) then succes = .true. return endif * end of logic for savedu = .true. endif * Here, reposs is .true., but either we hadn't saved the previous * solution, or else the RE error estimate is not small. * Save u in usave, and set savedu to .true. * Set double to .true. to indicate that the mesh should be doubled. * Set .onto6. to .false. to return to the top of the 4th order * iteration loop. call matcop(nudim, ncomp, ncomp, nmsh, u, usave) savedu = .true. double = .true. onto6 = .false. * end of logic for reposs = .true. endif * end of logic for linear endif if (pdebug .and. reposs .and. .not. onto6) write(6,912) if (.not. onto6) then * NB: onto6 can be false only for linear problems if (double) then call dblmsh (nmsh, nmax, xx, nmold, xxold, maxmsh) else * Refine the mesh near interval inmsh; the number of points * to be added depends on the relative size of dfexmx compared * to u and tol. drat = dfexmx/ * (max(one, abs(u(incmp,inmsh)))*tol(intol)) if (pdebug) write(6,913) drat, u(incmp,inmsh), tol(intol) numadd = drat**power call smpmsh (nmsh, nmax, xx, inmsh, numadd, * nmold, xxold, maxmsh) endif if (.not. maxmsh) call initu(ncomp, nmsh, xx, nudim, u) * end of logic for .not. onto6 endif return 901 format(1h ,'conv4') 902 format(1h ,'smooth') 903 format(1h ,'reaft6') 904 format(1h ,'smooth') 905 format(1h ,'callrt') 906 format(1h ,'oscchk') 907 format(1h ,'strctr') 908 format(1h ,'reposs') 909 format(1h ,'savedu') 910 format(1h ,'onto6 after decid4') 911 format(1h ,'rat1,oldrt1',2(1pe11.3)) 912 format(1h ,'reposs and not onto6') 913 format(1h ,'drat,u,tol',3(1pe11.3)) end subroutine fail4( ncomp, nmsh, nlbc, ntol, ltol, * xx, nudim, u, rhs, linear, nmax, * nmold, xxold, uold, tmwork, * iorder, iflnwt, itnwt, double, maxmsh, * numbig, nummed) implicit double precision (a-h,o-z) dimension ltol(ntol) dimension xx(*), u(nudim, *), rhs(*) dimension xxold(*), uold(ncomp, *), tmwork(*) logical linear, double, maxmsh logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 * The Newton procedure failed to obtain a 4th order solution. if (iprint .eq. 1) write(6,901) maxmsh = .false. if (iflnwt .eq. -1) then * iflnwt = -1 means that the Jacobian was considered singular. * (This is the only possible failure for a linear problem.) call dblmsh (nmsh, nmax, xx, nmold, xxold, maxmsh) call initu(ncomp, nmsh, xx, nudim, u) else * The routine mshref decides how to refine the mesh and then * performs the refinement, either by doubling or based on * the rhs vector at the best point. call mshref(ncomp, nmsh, nlbc, ntol, ltol, * iorder, rhs, tmwork, * nmax, xx, nmold, xxold, double, maxmsh, * numbig, nummed) if (.not. maxmsh) then if (linear .or. itnwt .eq. 0) then call initu(ncomp, nmsh, xx, nudim, u) else * Interpolate the partially converged solution. call matcop(nudim, ncomp, ncomp, nmold, u, uold) call interp(ncomp, nmsh, xx, nudim, u, nmold, * xxold, uold) endif endif * End of logic for failure because of some reason other than * singularity. endif return 901 format(1h ,'fail4') end subroutine conv6(ncomp, nmsh, ntol, ltol, tol, * nudim, u, uold, etest6, err6, * trst6, onto8, reaft6, succes) implicit double precision (a-h,o-z) dimension ltol(ntol) dimension u(nudim,*), tol(ntol) dimension uold(ncomp,*), etest6(*) logical trst6, onto8, reaft6, succes logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 logical errok * The Newton iteration converged for a 6th-order solution. if (iprint .eq. 1) write(6,901) succes = .false. * The logical flag reaft6 is true only when the 6th order solution * failed. Since the 6th order solution converged, reaft6 is false. reaft6 = .false. onto8 = .true. * Calculate the error estimates for the 4th order solution. call errest (ncomp, nmsh, ntol, ltol, tol, * nudim, u, uold, etest6, err6, errok) if (trst6 .and. errok) then succes = .true. return endif return 901 format(1h ,'conv6') end subroutine fail6( ncomp, nmsh, nlbc, ntol, ltol, tol, * nfxpnt, fixpnt, iorder, nmax, * xx, nudim, u, rhs, usave, xxold, uold, nmold, * ihcomp, irefin, rerr, ermx, tmwork, * reaft6, double, succes, maxmsh, * numbig, nummed) implicit double precision (a-h,o-z) dimension ltol(ntol) dimension fixpnt(*), tol(*), rhs(*) dimension xx(*), u(nudim,*), xxold(*) dimension uold(ncomp,*), usave(ncomp,*) dimension ihcomp(*), irefin(*) dimension rerr(ncomp,*), ermx(*), tmwork(*) logical reaft6, double, succes, maxmsh logical adjrer logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 * blas: dcopy parameter (eight = 8.0d+0) * nmpt is the standard number of mesh points to be added to selected * intervals when the mesh is altered based on the distribution * in size of the rhs vector. parameter ( nmpt = 15) * Non-convergence of 6th order. if (iprint .eq. 1) write(6,901) succes = .false. maxmsh = .false. * NB: the problem must be nonlinear. Linear problems will either * fail to converge for 4th order, or else, once they've converged * for 4th order, must converge for 6th order. * Restore the u array to the previous 4th order solution. call matcop(ncomp, nudim, ncomp, nmsh, uold, u) if (reaft6) write(6,9999) 9999 format(1h ,'in fail6, reaft6is true') if (.not.reaft6) write(6,9998) 9998 format(1h ,'in fail6, not reaft6') if (double) write(6,9997) 9997 format(1h ,'in fail6, double is true') if (.not.double) write(6,9996) 9996 format(1h ,'in fail6, not double') if (.not. reaft6 .or. .not. double) then * Here, either * (1) the mesh for which this 6th order solution failed * is not a doubled version of the immediately preceding mesh, or * (2) for the immediately preceding mesh, it is not true * that the 4th order converged and the 6th order failed. * Setting reaft6 to .true. signals that Richardson extrapolation * may be possible if the next 6th order solution fails. When * reaft6 is true, the routine conv4 immediately sets onto6 to true. reaft6 = .true. * Save the current 4th order solution in usave. call matcop(nudim, ncomp, ncomp, nmsh, u, usave) * Use the distribution of sizes in the rhs vector to refine the mesh. call mshref(ncomp, nmsh, nlbc, ntol, ltol, * iorder, rhs, tmwork, * nmax, xx, nmold, xxold, double, maxmsh, * numbig, nummed) if (.not. maxmsh) call interp(ncomp, nmsh, xx, nudim, u, * nmold, xxold, uold) else * Here, reaft6 and double are both true. So for two consecutive * meshes, the 4th order converged and the 6th order failed, * and the second mesh is the double of the first. * Calculate an error estimate from Richardson extrapolation * with the current and previous 4th order solutions. * (usave is the 4th order solution saved from the previous (halved) * mesh.) * Set addrer to .true. to signal that the rerr array should * be adjusted. adjrer = .true. call rerrvl( ncomp, nmsh, nudim, u, usave, ntol, ltol, * rerr, remax, itlmx, adjrer ) write(6,9994) 9994 format(1h ,'***in fail6') write(6,9993) remax, eight*tol(itlmx) 9993 format(1h ,'remax',1pe14.4,5x,'8*tol',1pe14.4) if (remax .lt. eight*tol(itlmx)) then succes = .true. else * Richardson extrapolation did not give sufficient accuracy. * Perform selective mesh refinement on the OLD (NB: old!) mesh * and the old (saved) solution, using the error estimate from * Richardson extrapolation to guide where the mesh points are placed. nmsh = 1 + (nmsh-1)/2 call dcopy(nmsh, xxold, 1, xx, 1) ipow = 4 * The rerr array is overwritten by selmsh. call selmsh(ncomp, nmsh, ntol, ltol, tol, * nfxpnt, fixpnt, ipow, nmax, * xx, ncomp, usave, rerr, irefin, ihcomp, * nmold, xxold, ermx, double, maxmsh) * If double is false on exit from selmsh, the call to selmsh has * produced a different (non-doubled) mesh. Interpolate the * saved solution (from the old mesh) onto the mesh newly created * by selmsh. * NB: Because double is false, we won't try Richardson extrapolation * if the next 4th order converges and 6th order fails. if (.not. maxmsh) then if (.not. double) then call interp(ncomp, nmsh, xx, nudim, u, nmold, * xxold, usave) else * Selective mesh refinement based on the old mesh simply * produced the same mesh that we started with. So now refine * starting with the doubled mesh (from before) and the solution. reaft6 = .true. * Save the solution in usave in case we can carry out Richardson * extrapolation in the same circumstances next time. call matcop(nudim, ncomp, ncomp, nmsh, u, usave) * Use the distribution of sizes in the rhs vector to refine the mesh. call mshref(ncomp, nmsh, nlbc, ntol, ltol, * iorder, rhs, tmwork, * nmax, xx, nmold, xxold, double, maxmsh, * numbig, nummed) if (.not. maxmsh) * call interp(ncomp, nmsh, xx, nudim, u, * nmold, xxold, usave) * end of logic for needing to refine (again) based on the * current mesh endif * end of logic for not too many mesh points endif * end of logic for failure of Richardson extrapolation * to produce a converged solution endif * end of logic for both reaft6 and double being true endif return 901 format(1h ,'fail6') end subroutine conv8( ncomp, nmsh, ntol, ltol, tol, * nfxpnt, fixpnt, linear, nmax, * xx, nudim, u, def, def6, def8, uold, * ihcomp, irefin, ermx, err6, * etest8, strctr, * double, nmold, xxold, maxmsh, succes, first8) implicit double precision (a-h,o-z) dimension ltol(ntol), tol(ntol) dimension fixpnt(*) dimension etest8(ntol) dimension xx(*), u(nudim,*), def(ncomp,*) dimension def6(ncomp,*), def8(ncomp,*), uold(ncomp,*) dimension ihcomp(*), irefin(*) dimension ermx(*), xxold(*) logical linear, strctr, double, maxmsh, succes, first8 logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 intrinsic max logical errok parameter (one = 1.0d+0, fourth = 0.25d+0, quan8 = 0.025d+0) parameter ( efact = 100.0d+0, huge = 1.0d+30 ) * blas: dload save er6old, er8old * The Newton iteration converged for the 8th order solution. if (iprint .eq. 1) write(6,901) if (first8) then er6old = huge er8old = huge first8 = .false. endif if (.not. linear) then call dload(ntol, one, etest8, 1) else do 10 i = 1, ntol etest8(i) = one/max(quan8, tol(i)**fourth) 10 continue endif succes = .false. maxmsh = .false. * Check estimated error. For a nonlinear problem, all components * of etest8 (the ratios used in testing the error) are set to one. * For a linear problem, the components of etest8 are in general * larger than one. But if strctr is .true. and the number of mesh * points decreased, we set the elements of etest8 to one (which * makes a stricter test). if (linear .and. strctr .and. nmsh .lt. nmold) * call dload(ntol, one, etest8, 1) call errest (ncomp, nmsh, ntol, ltol, tol, * nudim, u, uold, etest8, err8, errok) if (errok) then succes = .true. return endif * At this point, the 8th order solution converged, but did not * satisfy the test for termination. if (pdebug) write(6,902) err6, err8, er6old, er8old if (nmsh .lt. nmold. and. * err6 .gt. efact*er6old .and. * err8 .gt. efact*er8old) then * If the number of mesh points decreased and the errors in the * 6th and 8th order solutions did not decrease sufficiently compared * to the previous mesh, double the mesh and go back to try to * calculate a 4th order solution. call dblmsh (nmsh, nmax, xx, nmold, xxold, maxmsh) if (.not. maxmsh) then er6old = err6 er8old = err8 call initu(ncomp, nmsh, xx, nudim, u) endif return endif * Here, we know that * (1) the number of mesh points exceeds that for the previous mesh; or * (2) the number of mesh points decreased, the 6th and 8th order * errors did not satisfy the termination tests, but they did not * increase so much that the mesh needed to be doubled. er6old = err6 er8old = err8 if (err8 .le. err6) then * Perform selective mesh refinement based on the 8th order deferred * corrections. The value of ipow indicates that the error estimate * is of order 6. Then, for a nonlinear problem, interpolate the * latest solution onto the new mesh. ipow = 6 * NB: The array def8 will be overwritten by selmsh. call selmsh(ncomp, nmsh, ntol, ltol, tol, * nfxpnt, fixpnt, ipow, nmax, * xx, nudim, u, def8, irefin, ihcomp, * nmold, xxold, ermx, double, maxmsh) if (.not. maxmsh) then if (linear) then call initu(ncomp, nmsh, xx, nudim, u) else call matcop(nudim, ncomp, ncomp, nmsh, u, uold) call interp(ncomp, nmsh, xx, nudim, u, * nmold, xxold, uold) endif endif else * err8 is greater than err6 * For a linear problem, set all elements of etest8 to one, * which makes the error test stricter. (The elements of etest8 * may have already been set to one earlier in this routine.) if (linear) call dload(ntol, one, etest8, 1) * Selectively refine the mesh using the old solution and the * 6th order deferred correction. Then, for a nonlinear prpblem, * interpolate the old solution onto the new mesh. ipow = 4 * The array def6 will be overwritten by selmsh. call selmsh(ncomp, nmsh, ntol, ltol, tol, * nfxpnt, fixpnt, ipow, nmax, * xx, ncomp, uold, def6, irefin, ihcomp, * nmold, xxold, ermx, double, maxmsh) if (.not. maxmsh) then if (linear) then call initu(ncomp, nmsh, xx, nudim, u) else call interp(ncomp, nmsh, xx, nudim, u, * nmold, xxold, uold) endif endif * end of logic for err8 greater than err6 endif if (pdebug .and. .not.succes) write(6,903) return 901 format(1h ,'conv8') 902 format(1h ,'err6, err8, er6old, er8old',4(1pe11.3)) 903 format(1h ,'8th order fails error tests.') end subroutine fail8(ncomp, nmsh, nfxpnt, fixpnt, nmax, * ntol, ltol, tol, nmold, * xx, nudim, u, def6, xxold, uold, * ihcomp, irefin, ermx, double, maxmsh) implicit double precision(a-h,o-z) dimension fixpnt(*), ltol(ntol), tol(ntol) dimension xx(*), u(nudim,*), def6(ncomp,*) dimension xxold(*), uold(ncomp,*) dimension ihcomp(*), irefin(*) dimension ermx(*) logical double, maxmsh logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 if (pdebug) write(6,901) * 8th order solution did not converge (the problem must be nonlinear) ipow = 4 * Selectively refine the mesh based on the 6th order deferred * correction and the old solution. * The def6 array is overwritten by selmsh. call selmsh(ncomp, nmsh, ntol, ltol, tol, * nfxpnt, fixpnt, ipow, nmax, * xx, ncomp, uold, def6, irefin, ihcomp, * nmold, xxold, ermx, double, maxmsh) * Interpolate to obtain the new initial solution. if (.not. maxmsh) then call interp(ncomp, nmsh, xx, nudim, u, nmold, xxold, uold) endif return 901 format(1h ,'fail8') end subroutine dccal( ncomp, nmsh, ntol, ltol, * defexp, defimp, dfctol, fval, * ratdc, dfexmx, incmp, inmsh, intol, * derivm, dfimmx, rat1, rat2) implicit double precision (a-h,o-z) dimension ltol(ntol) dimension defexp(ncomp,nmsh-1), defimp(ncomp,nmsh-1) dimension fval(ncomp,nmsh), ratdc(nmsh-1) logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 parameter ( zero = 0.0d+0, one = 1.0d+0 ) parameter ( rtst = 50.0d+0, tstrat = 0.1d+0 ) intrinsic abs, max * blas: idamax * Find dfexmx, the maximum-magnitude element of defexp * in components for which a tolerance is specified. * The component index of dfexmx (incmp), its mesh * interval index (inmsh), and its tolerance index (intol), * are output parameters. dfexmx = zero do 10 it = 1, ntol icmp = ltol(it) idmx = idamax(nmsh-1, defexp(icmp, 1), ncomp) dval = abs(defexp(icmp, idmx)) if (dval .ge. dfexmx) then dfexmx = dval incmp = icmp inmsh = idmx intol = it endif 10 continue if (pdebug) then write(6,901) write(6,902) dfexmx, incmp, inmsh, intol endif * Find derivm (maximum-magnitude element of fval(incmp,*)) * for all mesh points. idmx = idamax(nmsh, fval(incmp, 1), ncomp) derivm = abs(fval(incmp, idmx)) if (pdebug) write(6,903) derivm * For component incmp, go through the mesh intervals to calculate * (1) dfimmx, the maximum implicit deferred correction; * (2) two crucial ratios, rat1 and rat2, used in deciding whether * to refine the mesh; * (3) the array ratdc of deferred-correction ratios (explicit to * implicit). * In defining rat1 and rat2, we consider only intervals for * which the explicit deferred correction (defexp) exceeds the * tolerance dfctol in magnitude. If it does not, the associated * interval does not affect rat1 or rat2, and the value of ratdc * is taken as 1. * rat2 is the maximum-magnitude ratio of sufficiently large * defexp to the larger of defimp and dfctol. * rat1 is the maximum-magnitude ratio of sufficiently large * defexp to the larger in magnitude of defimp and dfctol, but only * for those values of defexp greater than tstrat*dfexmx. * Thus by construction rat1 is less than or equal to rat2. rat1 = zero rat2 = zero dfimmx = zero smtest = tstrat*dfexmx do 100 im = 1, nmsh-1 texp = defexp(incmp, im) timp = defimp(incmp, im) dfimmx = max(dfimmx, abs(timp)) abtexp = abs(texp) if (abtexp .le. dfctol) then ratdc(im) = one else if (abs(timp) .lt. dfctol) timp = dfctol ratdc(im) = texp/timp abrat = abs(ratdc(im)) rat2 = max(rat2, abrat) if (abs(texp) .ge. smtest * .and. abrat .ge. rat1) rat1 = abrat endif * if (pdebug) write(6,904) im, texp, timp, ratdc(im), dfctol 100 continue if (pdebug) write(6,905) rat1, rat2, dfimmx return 901 format(1h ,'dccal') 902 format(1h ,'dfexmx, incmp, inmsh, intol',1pe11.3,3i5) 903 format(1h ,'derivm',1pe11.3) 904 format(1h ,'im, texp, timp, ratdc, dfctol',i5,4(1pe11.3)) 905 format(1h ,'rat1, rat2, dfimmx', 3(1pe11.3)) end subroutine decid4(linear, rat1, rat2, dfexmx, dfimmx, * derivm, dfold, tolval, oldrt1, * onto6, smooth, callrt, strctr, oscchk, double, reposs) implicit double precision (a-h,o-z) logical linear, onto6, smooth, callrt, strctr, * oscchk, double, reposs logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 logical stest parameter ( tenth = 0.1d+0, one = 1.0d+0, two = 2.0d+0 ) parameter ( thrtwo = 32.0d+0 ) parameter ( rtst = 50.0d+0, derval = 50.0d+0 ) * decid4 evaluates information about the deferred corrections * and the nature of the problem, and sets various logical * flags that control the subsequent logic of the algorithm. * This code has been written for clarity, and NOT for efficiency. onto6 = .true. callrt = .false. smooth = .false. oscchk = .false. strctr = .false. reposs = .false. double = .false. * rat2 is always greater than or equal to rat1. if (pdebug) write(6,901) if (pdebug) write(6,902) tolval, rtst stest = .true. if (linear) stest = dfexmx .lt. tenth*dfold if (rat2 .lt. rtst) then if (stest) then smooth = .true. else oscchk = .true. endif return endif * We know now that rat2 .ge. rtst. thttol = thrtwo*tolval if (pdebug) write(6,903) thttol if (rat1 .lt. rtst .and. dfexmx .lt. thttol) then if (stest) then smooth = .true. else oscchk = .true. endif return endif if (rat1 .lt. rtst .and. dfexmx .ge. thttol) then callrt = .true. return endif * We know now that rat1 .ge. rtst (and that rat2 .ge. rtst). if (derivm .gt. derval .and. dfexmx .lt. thttol) then if (stest) then smooth = .true. else oscchk = .true. endif return endif if (derivm .gt. derval .and. dfexmx .gt. thttol) then if (dfimmx .lt. one) then callrt = .true. else strctr = .true. if (linear) then onto6 = .false. if (two*rat1 .ge. oldrt1) double = .true. * end of logic for linear endif * end of logic for dfimmx .ge. one endif return * end of logic for derivm .gt. derval .and dfexmx .gt. thttol endif * To reach this point in the code, both of the following must hold: * rat1 .ge. rtst (which means that rat2 .ge. rtst) * derivm .le. derval * On linear problems, a special termination rule is tried if two * conditions hold: * (1) the 4th order solution has been computed on two consecutive * meshes, one of which is the double of the other * (this holds when double is .true.), and * (2) on both meshes, rat1 .ge. rtst, and derivm is small. When * the conditions in (2) hold for a particular mesh, decid4 * sets reposs to .true. to indicate that Richardson * extrapolation may be possible. * This set of tests is to take care of transients kept out by * initial conditions. if (linear) reposs = .true. return 901 format(1h ,'decid4') 902 format(1h ,'tolval, rtst',2(1pe11.3)) 903 format(1h ,'thttol',1pe11.3) end subroutine dfexcl (ncomp, nmsh, xx, nudim, u, defexp, fval, * tmp, fsub) implicit double precision (a-h, o-z) integer ncomp, nmsh dimension xx(nmsh), u(nudim,nmsh), fval(ncomp, nmsh) dimension defexp(ncomp,nmsh-1), tmp(ncomp,4) external fsub logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 parameter ( half = 0.5d+0, fourth = 0.25d+0, thfrth= 0.75d+0 ) common /consts/ alp1, alp2, alp3, bet0, bet2, bet3, bet4, * a1, b1, c1, d1, e2, f2, c2, d2, b2, a2, * p3, q3, e3, f3, c3, d3, a3, b3, a4, p4, x4, e4, c4, * a5, b5, c5, d5, e5, f5, a6, b6, c6 * Given the nmsh mesh points xx, the estimated solution * u and the array fval of function values at (xx(im), u(*,im)), * im = 1,...,nmsh, dfexcl calculates sixth-order explicit * deferred correction, stored in the array defexp, indexed * over the components and mesh intervals. * The array tmp is workspace for 4 intermediate vectors of * dimension ncomp. do 50 im = 1, nmsh-1 hmsh = xx(im+1) - xx(im) do 10 ic = 1, ncomp tmp(ic,1) = (a5*u(ic, im+1) + b5*u(ic, im)) * + hmsh*(c5*fval(ic,im)- d5*fval(ic,im+1)) tmp(ic,2) = (b5*u(ic,im+1) + a5*u(ic,im)) * + hmsh*(-c5*fval(ic,im+1) + d5*fval(ic,im)) 10 continue call fsub (ncomp, xx(im) + fourth*hmsh, tmp(1,1), * tmp(1,3)) call fsub (ncomp, xx(im) + thfrth*hmsh, tmp(1,2), * tmp(1,4)) do 20 ic = 1, ncomp tmp(ic,1) = half*(u(ic,im+1) + u(ic,im)) * + e5*hmsh*(fval(ic,im+1) - fval(ic,im)) * - f5*hmsh*(tmp(ic,4) - tmp(ic,3)) 20 continue call fsub(ncomp, half*(xx(im) + xx(im+1)), tmp(1,1), * tmp(1,2)) do 30 ic = 1, ncomp defexp(ic,im) = hmsh*(a6*(fval(ic,im+1) + fval(ic,im)) * + b6*(tmp(ic,3) + tmp(ic,4)) + c6*tmp(ic,2)) * - u(ic,im+1) + u(ic,im) 30 continue 50 continue return end subroutine df8cal (ncomp, nmsh, xx, nudim, u, fval, def8, * tmp, fsub) * Given the mesh points xx, the solution u, and the function * values fval, df8cal computes eighth-order deferred corrections, * which are stored in def8. * The array tmp is workspace for 8 intermediate vectors. implicit double precision (a-h, o-z) integer ncomp, nmsh dimension xx(nmsh), u(nudim,nmsh), fval(ncomp,nmsh) dimension def8(ncomp, nmsh-1), tmp(ncomp,8) external fsub logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 parameter ( half = 0.5d+0, two = 2.0d+0 ) parameter ( fc1 = 0.625d+0, fc2= 0.375d+0 ) common /consts/ alp1, alp2, alp3, bet0, bet2, bet3, bet4, * a1, b1, c1, d1, e2, f2, c2, d2, b2, a2, * p3, q3, e3, f3, c3, d3, a3, b3, a4, p4, x4, e4, c4, * a5, b5, c5, d5, e5, f5, a6, b6, c6 do 100 im = 1, nmsh-1 hmsh = xx(im+1) - xx(im) do 10 ic = 1, ncomp tmp(ic,1) = a1*u(ic,im+1) + b1*u(ic,im) * + hmsh*(c1*fval(ic,im+1) + d1*fval(ic,im)) tmp(ic,2) = b1*u(ic,im+1) + a1*u(ic,im) * - hmsh*(c1*fval(ic,im) + d1*fval(ic,im+1)) 10 continue call fsub(ncomp, xx(im) + fc1*hmsh, tmp(1,1), tmp(1,3)) call fsub(ncomp, xx(im) + fc2*hmsh, tmp(1,2), tmp(1,4)) do 20 ic = 1, ncomp tmp(ic,1) = a2*u(ic,im+1) + b2*u(ic,im) * + hmsh*(c2*fval(ic,im+1) + d2*fval(ic,im) * + e2*tmp(ic,3) + f2*tmp(ic,4)) tmp(ic,2) = b2*u(ic,im+1) + a2*u(ic,im) * - hmsh*(d2*fval(ic,im+1) + c2*fval(ic,im) * + f2*tmp(ic,3) + e2*tmp(ic,4)) 20 continue call fsub(ncomp, xx(im) + (half + alp2)*hmsh, tmp(1,1), * tmp(1,5)) call fsub(ncomp, xx(im) + (half - alp2)*hmsh, tmp(1,2), * tmp(1,6)) do 30 ic = 1, ncomp tmp(ic,1) = a3*u(ic,im+1) + b3*u(ic,im) * + hmsh*(c3*fval(ic,im+1) + d3*fval(ic,im) * + e3*tmp(ic,3) + f3*tmp(ic,4) * + p3*tmp(ic,5) + q3*tmp(ic,6)) tmp(ic,2) = b3*u(ic,im+1) + a3*u(ic,im) * - hmsh*(d3*fval(ic,im+1) + c3*fval(ic,im) * + f3*tmp(ic,3) + e3*tmp(ic,4) * + q3*tmp(ic,5) + p3*tmp(ic,6)) 30 continue call fsub (ncomp, xx(im) + (half + alp3)*hmsh, tmp(1,1), * tmp(1,7)) call fsub (ncomp, xx(im) + (half - alp3)*hmsh, tmp(1,2), * tmp(1,8)) do 40 ic = 1, ncomp tmp(ic,1) = a4*(u(ic,im+1) + u(ic,im)) * + hmsh*(c4*(fval(ic,im+1) - fval(ic,im)) * + e4*(tmp(ic,3) - tmp(ic,4)) * + x4*(tmp(ic,7) - tmp(ic,8))) 40 continue call fsub (ncomp, xx(im) + half*hmsh, tmp(1,1), tmp(1,2)) do 50 ic = 1, ncomp def8(ic,im) = * hmsh*(bet0*(fval(ic,im) + fval(ic,im+1)) * + bet2*(tmp(ic,5) + tmp(ic,6)) * + bet3*(tmp(ic,7) + tmp(ic,8)) * + two*bet4*tmp(ic,2)) * - u(ic,im+1) + u(ic,im) 50 continue 100 continue return end subroutine dfimcl( ncomp, nmsh, defexp, chold, dsq, dexr, * ipivot, defimp) implicit double precision (a-h,o-z) dimension defexp(ncomp, nmsh-1), chold(ncomp, ncomp, nmsh-1) dimension dsq(ncomp, ncomp), dexr(ncomp) dimension ipivot(ncomp), defimp(ncomp, nmsh-1) logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 * blas: dcopy parameter (zero = 0.0d+0) * dfimcl calculates the rational deferred correction array, * which is indexed over the components and mesh intervals. call mtload(ncomp, nmsh-1, zero, ncomp, defimp) do 100 im = 1, nmsh-1 call dcopy(ncomp, defexp(1,im), 1, dexr(1), 1 ) do 50 ic = 1, ncomp call dcopy(ncomp, chold(1,ic,im), 1, dsq(1,ic), 1) 50 continue call lufac (ncomp, ncomp, dsq, ipivot, ierlu) if (ierlu .eq. 0) then call lusol (ncomp, ncomp, dsq, ipivot, dexr, * defimp(1, im)) endif 100 continue return end subroutine osc (ncomp, nmsh, dfexmx, incmp, * defcor, ratdc, double, inmsh, onto6, trst6, smooth) implicit double precision (a-h, o-z) dimension defcor(ncomp, *), ratdc(*) logical double, onto6, trst6, smooth logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 intrinsic abs parameter ( zero = 0.0d+0, half = 0.5d+0 ) parameter ( frac1 = 0.1d+0, frac2 = 1.0d-2 ) * For linear problems, subroutine osc performs heuristic tests * to detect an oscillating solution. the tests check whether * (significant) explicit and implicit deferred corrections have * different (componentwise) signs. * dfexmx is the maximum-magnitude explicit deferred correction, * and is known to occur in component incmp. * The array defcor contains the explicit deferred corrections. * The array ratdc contains the ratios of explicit to implicit * deferred corrections. * jsndif counts the number of differences in sign. jsndif = 0 rmax = zero * allsum is the sum of the magnitudes of all deferred corrections, * smlsum is the sum of the magnitudes of the small deferred * corrections, and bigsum is the sum of the magnitudes of the * large deferred corrections. Here, small is defined as less * than half of the maximum. ninter = nmsh - 1 if (pdebug) write(6,901) allsum = zero smlsum = zero bigsum = zero ibig = 0 ism = 0 do 30 im = 1, ninter abdef = abs(defcor(incmp,im)) allsum = allsum + abdef if (abdef .lt. half*dfexmx) then ism = ism + 1 smlsum = smlsum + abdef else ibig = ibig + 1 bigsum = bigsum + abdef endif * The counter of sign differences is incremented if (1) ratdc is negative * (which means that the two deferred corrections have opposite * sign) and (2) the explicit deferred correction is not too small * relative to the maximum. if (pdebug) write(6,902) im, ratdc(im), abdef, frac2*dfexmx if (ratdc(im).lt.zero .and. abdef.ge.frac2*dfexmx) then jsndif = jsndif + 1 * If more than 4 sign differences have occurred, exit after setting * double to .true., which signals that the mesh * should be doubled (i.e., twice as many intervals). if (jsndif.gt.4) then onto6 = .false. double = .true. return endif if (abs(ratdc(im)).ge.rmax) then rmax = abs(ratdc(im)) inmsh = im endif endif 30 continue if (pdebug) write(6,903) rmax, jsndif avsm = zero if (ism.gt.0) avsm = smlsum/ism avbg = zero if (ibig.gt.0) avbg = bigsum/ibig ave = allsum/ninter if (pdebug) write(6,904) ave, avsm, avbg if (avsm.gt.frac1*avbg .or. ave.gt.half*avbg) then * The error appears to be uniformly large. * Signal that the 6th order solution should be calculated. onto6 = .true. elseif (jsndif.eq.0) then * If there were no sign changes, the problem appears to be smooth. smooth = .true. onto6 = .true. else * If the sign changed at between 1 and 4 points, don't go on to * 6th order, and don't ever accept a 6th order solution even if the * error estimate at a later stage indicates that it is OK to do so. * Set double to .false., to signal that the mesh will not necessarily * be doubled. double = .false. onto6 = .false. trst6 = .false. endif return 901 format(1h ,'osc') 902 format(1h ,'im, ratdc, abdef, val',i5,3(1pe11.3)) 903 format(1h ,'rmax, jsndif', 1pe11.3,i5) 904 format(1h ,'ave, avsm, avbg', 3(1pe11.3)) end subroutine ratcor ( ncomp, nmsh, xx, defimp, bhold, dfrat) implicit double precision (a-h, o-z) dimension xx(nmsh), defimp(ncomp,nmsh-1) dimension dfrat(ncomp,nmsh-1), bhold(ncomp,ncomp,nmsh-1) * blas: ddot, dscal parameter (zero = 0.0d+0, half = 0.5d+0, one = 1.0d+0) ninter = nmsh - 1 do 10 im = 1, ninter hmsh = xx(im+1) - xx(im) call dscal(ncomp*ncomp, (-half*hmsh), bhold(1,1,im), 1) 10 continue do 20 im = 1, ninter do 20 ic = 1, ncomp bhold(ic,ic,im) = bhold(ic,ic,im) + one 20 continue do 30 im = 1, ninter do 30 ic = 1, ncomp dfrat(ic,im) = ddot(ncomp, bhold(ic,1,im), ncomp, * defimp(1,im), 1) 30 continue return end subroutine stcons implicit double precision (a-h,o-z) * stcons computes constants needed in integration formulae * and stores them in a labeled common area. parameter ( one = 1.0d+0, four = 4.0d+0, two = 2.0d+0 ) parameter ( five = 5.0d+0, three = 3.0d+0 ) parameter ( half = 0.5d+0, fourth = 0.25d+0 ) common /consts/ alp1, alp2, alp3, bet0, bet2, bet3, bet4, * a1, b1, c1, d1, e2, f2, c2, d2, b2, a2, * p3, q3, e3, f3, c3, d3, a3, b3, a4, p4, x4, e4, c4, * a5, b5, c5, d5, e5, f5, a6, b6, c6 alp1 = one/8.0d+0 alp1sq = one/64.0d+0 alp2sq = five/28.0d+0 alp3sq = five/84.0d+0 alp2 = sqrt(alp2sq) alp3 = sqrt(alp3sq) bet0 = one/6.0d+0 - (10.0d+0 - 28.0d+0*(alp2sq + alp3sq))/ * (105.0d+0*(one - four*alp2sq)* * (one - four*alp3sq)) bet2 = -(28.0d+0*alp3sq - three)/ * (1680.0d+0*alp2sq* * (one - four*alp2sq)*(alp2sq - alp3sq)) bet3 = (28.0d+0*alp2sq - three)/ * (1680.0d+0*alp3sq* * (one - four*alp3sq)*(alp2sq - alp3sq)) bet4 = half - bet0 - bet2-bet3 a1 = half*(one - alp1)*(two*alp1 + one)* * (two*alp1 + one) b1 = half*(one + alp1)* * (two*alp1 - one)*(two*alp1 - one) c1 = half*(alp1sq - fourth)*(two*alp1 + one) d1 = half*(alp1sq - fourth)*(two*alp1 - one) uu = alp2*((four*alp2sq - one)**2)/ * ((four*alp1sq - one)*(20.0d+0*alp1*alp1 - one)) vv = ((four*alp2sq - one)**2)/ * (16.0d+0*alp1*(four*alp1sq - one)) e2 = half*(uu + vv) f2 = half*(uu - vv) rr = half*(alp2*(four*alp2sq - one) + * (one - 12.0d+0*alp1sq)*(e2 + f2)) ss = fourth*(four*alp2sq - one) - two*alp1*(e2 - f2) c2 = half*(rr + ss) d2 = half*(rr - ss) ww = two*(alp2 - (c2 + d2 + e2 + f2)) b2 = half*(one - ww) a2 = half*(one + ww) z1 = (three - 28.0d+0*alp3sq)/ * (1680.0d+0*alp2*(four*alp2sq - one)* * (alp2*alp2 - alp3sq)*bet3) z2 = one/(105.0d+0*alp3*bet3* * (20.0d+0*alp2sq - one)*(four*alp2sq - one)) p3 = half*(z1 + z2) q3 = half*(z2 - z1) u1 = (alp3*((four*alp3sq - one)**2)- * (p3 + q3)*(20.0d+0*alp2sq - one) * *(four*alp2sq - one))/ * ((four*alp1sq - one)*(20.0d+0*alp1sq - one)) v1 = (alp3sq*(one - two*alp3sq)- * two*alp2*(one - four*alp2sq)*(p3 - q3) * -one/8.0d+0)/(two*alp1*(one - four*alp1sq)) e3 = half*(u1 + v1) f3 = half*(u1 - v1) r1 = half*(alp3*(four*alp3sq - one) + * (e3 + f3)*(one - 12.0d+0*alp1sq) + * (p3 + q3)*(one - 12.0d+0*alp2sq)) s1 = alp3sq - fourth - two*alp1*(e3 - f3) * - two*alp2*(p3 - q3) c3 = half*(r1 + s1) d3 = half*(r1 - s1) w1 = two*(alp3 - (c3 + d3 + e3 + f3 + p3 + q3)) a3 = half*(one + w1) b3 = half*(one - w1) a4 = half p4 = 0.0d+0 x4 = (three - 28.0d+0*alp2sq)/ * (3360.0d+0*alp3*bet4*(four*alp3sq - one) * *(alp3sq - alp2sq)) e4 = (0.125d+0 + four*alp2*p4* * (one - four*alp2sq) + * four*alp3*x4*(one - four*alp3sq))/ * (four*alp1*(four*alp1sq - one)) c4 = -(0.125d+0 + two*alp1*e4 + two*alp2*p4 + * two*alp3*x4) a5 = five/32.0d+0 b5 = 27.0d+0/32.0d+0 c5 = 9.0d+0/64.0d+0 d5 = three/64.0d+0 e5 = five/24.0d+0 f5 = two/three a6 = 7.0d+0/90.0d+0 b6 = 16.0d+0/45.0d+0 c6 = two/15.0d+0 return end subroutine fixjac(ncomp, nmsh, nlbc, * iorder, ntol, ltol, tol, * xx, nudim, u, defcor, defnew, delu, * rhs, fval, utrial, rhstri, * rnsq, uint, ftmp, tmprhs, * ajac, topblk, botblk, ipivot, * fsub, gsub, iflag) * Fixed Jacobian iterations. implicit double precision (a-h,o-z) dimension ltol(ntol), tol(ntol) dimension xx(nmsh), u(nudim,nmsh), defcor(ncomp,nmsh-1) dimension defnew(ncomp,nmsh-1), delu(ncomp,nmsh) dimension rhs(ncomp*nmsh), fval(ncomp,nmsh) dimension utrial(ncomp,nmsh), rhstri(ncomp*nmsh) dimension uint(ncomp), ftmp(ncomp), tmprhs(ncomp*nmsh) dimension ajac(ncomp, 2*ncomp, nmsh-1) dimension topblk(nlbc,ncomp), botblk(ncomp-nlbc,ncomp) dimension ipivot(ncomp*nmsh) logical better external fsub, gsub logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 common/mchprs/flmin, flmax, epsmch intrinsic abs, max * blas: dcopy, dssq parameter ( one = 1.0d+0 ) parameter ( xlarge = 1.0d+6, huge = 1.0d+30, lmtfrz = 8) parameter ( rngrow = 16.0d+0, rfact = 100.0d+0 ) parameter ( tolfct = 0.1d+0 ) * The iteration scheme uses a fixed Jacobian matrix to solve for * correction vectors, once there has been convergence of the Newton * iterations on this mesh. It is assumed that the LU * factors of the Jacobian have been left unaltered since * their calculation. if (iprint .eq. 1) write(6,901) ninter = nmsh - 1 rnold = flmax isize=nmsh*ncomp * Evaluate the right-hand side rhstri at the initial solution u by * adding the new deferred corrections to the already-calculated * rhs vector. call dcopy(nlbc, rhs, 1, rhstri, 1) ind = nlbc do 10 im = 1, ninter do 10 ic = 1, ncomp ind = ind + 1 rhstri(ind) = rhs(ind) + defnew(ic, im) 10 continue ind = ninter*nmsh + nlbc + 1 call dcopy(ncomp-nlbc, rhs, 1, rhstri, 1) call dssq ( nmsh*ncomp, rhstri, 1, scale, sumsq ) rnsq = (scale**2)*sumsq iter = 0 * If the initial right-hand side is too large, do not even attempt to * solve the nonlinear equations. if (rnsq.gt.huge .or. * (iorder.eq. 8 .and. rnsq.gt.xlarge)) then if (iprint .eq. 1) write (6,902) rnsq iflag = -2 return end if call dcopy(ncomp*nmsh, rhstri, 1, rhs, 1) * Statement 100 is the top of the iteration loop. 100 continue * If rnsq is sufficiently small, terminate immediately. if (iprint .eq. 1) write(6,903) iter, rnsq if (rnsq .le. epsmch) then iflag = 0 return endif iter = iter + 1 * Solve for the step delu by solving a system involving the fixed * Jacobian (whose LU factors are saved). Copy the rhs array into * tmprhs, which is then overwritten by blkslv. call dcopy(ncomp*nmsh, rhs, 1, tmprhs, 1) call crslve(Topblk, Nlbc, Ncomp, Ajac, Ncomp, 2*Ncomp, + Ninter, Botblk, Ncomp-Nlbc, Ipivot, Tmprhs, Delu) * Compute the trial point utrial by adding delu to u. call matcop( nudim, ncomp, ncomp, nmsh, u, utrial ) call maxpy( ncomp, nmsh, one, delu, ncomp, utrial ) * compute the right-hand side vector rhstri and its squared * two-norm at the trial point. rnold = rnsq call fneval(ncomp, nmsh, xx, ncomp, utrial, fval, fsub) call rhscal (ncomp, nmsh, nlbc, xx, ncomp, utrial, defcor, * fsub, gsub, rhstri, rnsq, fval, ftmp, uint) * If rnsq strictly decreased, update the solution vector u * and the right-hand side rhs. better = .false. if (rnsq .lt. rnold) then better = .true. call matcop( ncomp, nudim, ncomp, nmsh, utrial, u ) call dcopy( ncomp*nmsh, rhstri, 1, rhs, 1 ) endif * Stop the fixed Jacobian iterations if there have been too * many iterations, or if rnsq has not decreased by a factor * of at least rngrow. if (iter .ge. lmtfrz .or. rnsq .gt. (rnold/rngrow)) then if (better) then * Setting iflag to -3 signals that, although the fixed Jacobian * iterations did not succeed, the current point was an improvement * on the previous one. Hence, if we switch to a Newton procedure, * the right-hand side does not need to be recalculated. iflag = -3 else iflag = -2 endif if (iprint .eq. 1) write(6,904) iflag return endif * Test for convergence using the ratio abs((change in u)/max(u,1)). do 150 im = 1, nmsh do 150 it = 1, ntol itol = ltol(it) er = abs(delu(itol,im))/max(abs(u(itol,im)), one) if (er .gt. tolfct*tol(it)) go to 100 150 continue * To exit from the loop here, the convergence tests have * been passed. if (iprint .ge. 0) write(6,905) iter, rnsq iflag = 0 return 901 format(1h ,'fixed Jacobian iterations') 902 format(1h ,'Large residual, rnsq =',1pe12.4) 903 format(1h ,'iter, rnsq',i5,1pe11.3) 904 format(1h ,'failure of fixed Jacobian, iflag =',i5) 905 format(1h ,'fixed Jacobian convergence',i5,1pe11.3) end subroutine lineq( ncomp, nmsh, nlbc, * ludone, xx, nudim, u, defcor, * delu, rhs, fval, * uint, ftmp, dftmp1, dftmp2, dgtm, tmprhs, * ajac, topblk, botblk, bhold, chold, ipivot, * fsub, dfsub, gsub, dgsub, iflag) implicit double precision (a-h,o-z) dimension xx(nmsh), u(nudim, nmsh), defcor(ncomp, nmsh-1) dimension delu(ncomp, nmsh), rhs(ncomp*nmsh) dimension fval(ncomp,nmsh), uint(ncomp), ftmp(ncomp) dimension topblk(nlbc,*), botblk(ncomp-nlbc,*) dimension dftmp1(ncomp, ncomp), dftmp2(ncomp, ncomp) dimension dgtm(ncomp), tmprhs(ncomp*nmsh) dimension ajac(ncomp, 2*ncomp, nmsh-1), * bhold(ncomp, ncomp, nmsh-1), * chold(ncomp, ncomp, nmsh-1) dimension ipivot(ncomp*nmsh) logical ludone external fsub, dfsub, gsub, dgsub logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 * blas: dcopy, dload parameter ( one = 1.0d+0, zero = 0.0d+0 ) * The routine lineq calculates the Newton step for a linear * problem. The Newton step is exact unless the Jacobian * matrix is singular. isize=nmsh*ncomp ninter = nmsh - 1 if (.not. ludone) then * Compute the right-hand side vector rhs. call lnrhs (ncomp, nmsh, nlbc, xx, nudim, u, * fsub, gsub, rhs, rnsq, fval, ftmp, uint) * If the Jacobian for this mesh has not previously been * calulated and factorized successfully, call jaccal. * The block-structured Jacobian matrix is stored in three * matrices (topblk, ajac, and botblk). * The matrices bhold and chold are also calculated in jaccal, * and are saved for later use in outer routines. call jaccal (ncomp, nmsh, nlbc, * xx, nudim, u, fval, dgtm, dftmp1, dftmp2, uint, * ajac, topblk, botblk, bhold, chold, * dfsub, dgsub) * Call blkdcm to calculate the LU factors of the Jacobian. * The factors are overwritten on the matrices topblk, ajac and botblk. * Interchanges are represented in the integer array ipivot. call dcopy(ncomp*nmsh,rhs,1,tmprhs,1) call colrow(isize, topblk,nlbc, ncomp, ajac, ncomp, 2*ncomp, + ninter, botblk, ncomp-nlbc, ipivot, tmprhs, delu, iflag) ludone = .true. * Copy the rhs into the temporary vector tmprhs, which will be * overwritten by blkslv. else * The right-hand side is the deferred correction array, * padded with zeros at the boundary conditions. call dload(nlbc, zero, tmprhs(1), 1) do 100 im = 1, ninter loc = (im-1)*ncomp + nlbc + 1 call dcopy(ncomp, defcor(1,im), 1, tmprhs(loc), 1) 100 continue nrhs = ninter*ncomp + nlbc + 1 call dload(ncomp-nlbc, zero, tmprhs(nrhs), 1) call crslve(topblk,nlbc,ncomp,ajac,ncomp,2*ncomp,ninter, + botblk,ncomp-nlbc,ipivot,tmprhs,delu) endif * Since the problem is linear, the Newton step is exact. The * new u array is obtained by adding delu to u. call maxpy ( ncomp, nmsh, one, delu, nudim, u ) iflag = 0 return 901 format(1h ,'Singular matrix') end subroutine newteq(ncomp, nmsh, nlbc, * rhsgiv, ntol, ltol, tol, * xx, nudim, u, defcor, * delu, rhs, fval, * utrial, rhstri, * uint, ftmp, dftmp1, dftmp2, dgtm, tmprhs, xmerit, * ajac, topblk, botblk, bhold, chold, ipivot, * fsub, dfsub, gsub, dgsub, iter, iflag) implicit double precision (a-h,o-z) dimension ltol(*), tol(*), xx(*) dimension fval(ncomp,*) dimension u(nudim, *), delu(ncomp, *), utrial(ncomp,nmsh) dimension rhs(ncomp*nmsh), defcor(ncomp,*) dimension ajac(ncomp, 2*ncomp, *) dimension topblk(nlbc,*), botblk(ncomp-nlbc,*) dimension ftmp(*), uint(*), dgtm(ncomp) dimension dftmp1(ncomp, ncomp), dftmp2(ncomp, ncomp) dimension bhold(ncomp, ncomp, *), chold(ncomp, ncomp, *) dimension ipivot(*) dimension rhstri(ncomp*nmsh) dimension tmprhs(ncomp*nmsh), xmerit(ncomp, nmsh) logical rhsgiv external fsub, dfsub, gsub, dgsub parameter ( zero = 0.0d+0, one = 1.0d+0 ) parameter ( two = 2.0d+0, half = 0.5d+0, fourth = 0.25d+0 ) parameter ( tenth = 0.1d+0, ten = 10.0d+0, hund = 100.0d+0 ) logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 common/mchprs/flmin, flmax, epsmch logical gtpdeb, imprvd, braktd, crampd, extrap, vset, wset save gtpdeb, mfsrch, epsaf, epsag, eta, rmu, tolabs, alfmax save tolrel, toltny intrinsic abs, max * blas: dcopy logical frscal save frscal parameter (cnvfct = 0.1d+0 ) data frscal/.true./ data alfsml/1.0d-4/, alfmax/1.1d+0/ data imerit/1/, lmtnwt/39/ data shrfct/100.0d+0/, stpfct/2.0d+0/ data gtpdeb/.false./, mfsrch/5/ data eta/.999999d+0/, rmu/1.0d-6/ * The routine newteq performs Newton iterations with a line * search, to solve the nonlinear equations. * Set up constants if this is the first call to newteq. if (frscal) then frscal = .false. epsaf = epsmch epsag = epsmch tolabs = epsmch tolrel = epsmch toltny = epsmch endif ninter = nmsh - 1 if (iprint .eq. 1) write(6,901) * A Newton method with line search and watchdog safeguarding * is used to try to solve the nonlinear equations. * Initialize iter (the counter of Newton iterations) and alfold * (the step taken at the previous iteration). iter = -1 alfold = one alfa = zero rnbest = flmax if (.not. rhsgiv) then * If necessary, evaluate the right-hand side at the initial u. call rhscal (ncomp, nmsh, nlbc, xx, nudim, u, defcor, * fsub, gsub, rhs, rnsq, fval, ftmp, uint) endif * At any given Newton iteration, rnprev is the value of rnsq at * the immediately preceding Newton iteration. rnprev = flmax if (.not. pdebug .and. iprint .eq. 0) write (6,902) * Initialize counter of watchdog iterations. itwtch = 0 * Statement 100 is the top of the Newton iteration loop. 100 continue iter = iter + 1 if (iprint .eq. 1) write(6,910) iter * If there have been too many Newton iterations, terminate. if (iter .ge. lmtnwt) then if (iprint .ge. 0) write(6,903) iflag = -2 return endif * The vector rhs is the right-hand side at the current iterate, * and rnsq is its squared two-norm. * Perform watchdog tests, using the unscaled merit function (rnsq) * as the watchdog function. The routine wtchdg updates rnbest * and itwtch. If iflwat is not zero, this sequence of Newton * iterations is terminated. call wtchdg ( iter, rnsq, rnbest, rnprev, itwtch, * alfold, iflwat ) if (iflwat .ne. 0) then if (iprint .ge. 0) write(6,904) iter iflag = -3 return endif * Watchdog tests are passed. Proceed with the Newton iteration. * Call jaccal to evaluate the block-structured Jacobian matrix, * which is stored in three matrices (topblk, ajac, and botblk). * The matrices bhold and chold are saved for use in later * calculations in the outer routine. * If rnsq is sufficiently small, terminate immediately. * Note that the stored Jacobian does not correspond exactly * to the final point. if (rnsq .le. epsmch) then if (iprint .ge. 0) write(6,906) iter, rnsq iflag = 0 return endif call jaccal (ncomp, nmsh, nlbc, * xx, nudim, u, fval, dgtm, dftmp1, dftmp2, uint, * ajac, topblk, botblk, bhold, chold, * dfsub, dgsub) * blkdcm is called to calculate the LU factors of the Jacobian, * which are overwritten on topblk, ajac and botblk. * Interchanges are represented in the integer array ipivot. * Solve for the Newton step delu. Copy the rhs array into tmprhs, * which is then overwritten by blkslv. call dcopy(ncomp*nmsh, rhs, 1, tmprhs, 1) call colrow(Nmsh*ncomp,topblk,nlbc,ncomp,ajac,ncomp,2*ncomp, + ninter,botblk,ncomp-nlbc,ipivot,tmprhs,delu,iflag) * If imerit = 1, the line search is based on the scaled merit function, * the squared two-norm of the solution xmerit of the linear system * (Jacobian)*xmerit = rhs, * where (Jacobian) is the Jacobian at the current Newton iterate. * Thus the initial value of the scaled merit function is simply * the squared two-norm of the Newton step delu itself. if (imerit.eq.1) then call mssq( ncomp, nmsh, delu, xmscal, xmsq ) fmtry = (xmscal**2)*xmsq else * The unscaled merit function is simply the squared two-norm of rhs. fmtry = rnsq end if c fa and oldg represent the merit function and its gradient c at the initial point of the line search. fa = fmtry oldg = -two*fa alfa = zero if (iprint .eq. 1) write (6,908) alfa, fmtry, rnsq * On the first Newton iteration, the initial trial step is unity. * On subsequent iterations, the initial step is not allowed to * be more than the factor stpfct larger than the final step at * the immediately preceding iteration. alfa = one if(stpfct*alfold .lt. one) alfa = stpfct*alfold if (alfa .lt. alfsml) alfa = alfsml fmold = fa inform = -1 * Statement 150 is the top of the inner line search iteration. * The line search routine getptq has been altered so that it * terminates with an indication of success as soon as a * strictly lower value of the merit function is found. Note that * this is a much less strict requirement than the usual sufficient * decrease conditions. 150 continue iwr = 6 call getptq (gtpdeb, mfsrch, iwr, alfmax, alfsml, alfuzz, * epsaf, epsag, * eta, fmtry, fmold, oldg, rmu, tolabs, tolrel, toltny, * imprvd, inform, nfsrch, alfa, alfbst, fbest, * braktd, crampd, extrap, vset, wset, nsamea, nsameb, * alin, blin, fa, factor, fv, fw, xtry, xv, xw) * inform = 1, 2 or 3 indicates success in finding an acceptable point. * inform = 4 means alfmax is too small (this should never happen here, * since alfmax is set always to 1.1). * inform = 5 means that a decrease was not achieved for any step * greater than alfsml. * inform = 6 means a better point could not be found (the minimum * probably lies too close to alfa=0). * inform = 7 means that the gradient at alfa=0 (oldg) is positive * (this cannot happen here, since oldg=-two*fa, and fa is a non-negative * number) if (pdebug) write(6,907) inform, alfa if (inform .eq. 5) then iflag = -5 return elseif (inform .eq. 4 .or. inform .eq. 7) then iflag = -4 return elseif (inform .eq. 0) then * inform = 0 means that a new function value should be obtained * with the step alfa. * We may override alfa from getptq by requiring that the step is not * allowed to decrease by more than a factor of shrfct during * a line search iteration. * if (alfa .lt. alfold/shrfct) alfa = alfold/shrfct alfold = alfa * Define the next iterate utrial = u + alfa*delu. * Call fneval and rhscal to evaluate the right-hand side * rhstri at utrial. * The vector rhstri is stored separately, and rhs is overwritten * only when an improved point is found. call matcop ( nudim, ncomp, ncomp, nmsh, u, utrial) call maxpy ( ncomp, nmsh, alfa, delu, ncomp, utrial ) call fneval(ncomp, nmsh, xx, ncomp, utrial, fval, fsub) call rhscal (ncomp, nmsh, nlbc, xx, ncomp, utrial, defcor, * fsub, gsub, rhstri, rnsqtr, fval, ftmp, uint) fmold = fmtry if (imerit .eq. 1) then * Solve a linear system to obtain the 2-d array xmerit whose squared * norm is the scaled merit function. The LU factors of the Jacobian * have already been calculated by blkdcm. * Copy rhstri into tmprhs, which is overwritten by blkslv. call dcopy(ncomp*nmsh, rhstri, 1, tmprhs, 1) call crslve(topblk, nlbc, ncomp, ajac, ncomp, 2*ncomp, ninter, + botblk, ncomp-nlbc, ipivot, tmprhs, xmerit) call mssq( ncomp, nmsh, xmerit, xscale, xsolsq ) fmtry = (xscale**2)*xsolsq else * The unscaled merit function is the squared two-norm of the right-hand * side. fmtry = rnsqtr end if if (iprint .eq. 1) write (6,908) alfa, fmtry, rnsqtr go to 150 endif * To reach here, inform must be 1, 2, 3, or 6, and the line search * has found a strictly lower value of the merit function. * Store the new Newton iterate in u, and the corresponding rhs * vector in rhs. rnprev = rnsq rnsq = rnsqtr call matcop (ncomp, nudim, ncomp, nmsh, utrial, u) call dcopy(ncomp*nmsh, rhstri, 1, rhs, 1) if (iprint .eq. 0) write(6,909) iter, alfa, fmtry, rnsq * Now test for convergence using the ratio of the Newton step * for each component with max(1, abs(current solution estimate)). * If the test fails for any element of u, branch back to the * top of the Newton iteration. do 160 im = 1, nmsh do 160 it = 1, ntol icmp = ltol(it) er = abs(delu(icmp,im))/max(abs(u(icmp,im)), one) if (er .gt. cnvfct*tol(it)) go to 100 160 continue if (iprint .eq. 0) write(6, 906) iter+1, rnsq iflag = 0 * To fall through the above loop, the termination test for a * sufficiently small delu is satisfied. * Note that the stored Jacobian and its factorization do not * correspond to the final solution. return 901 format(1h ,'start Newton iterations') 902 format(1h ,' iter', * 7x,'alfa',6x,'merit',7x,'rnsq') 903 format(1h ,'Too many Newton iterations') 904 format(1h ,'Watchdog tests fail, iter =', i5) 905 format(1h ,'Singular Jacobian, iter=',i5) 906 format(1h ,'Convergence, iter =',i5,4x,'rnsq =',1pe12.3) 907 format(1h ,'inform, alfa after getptq',i5,3x, 1pe11.3) 908 format(1h ,'alfa, merit, rnsq',3(1pe11.3)) 909 format(1h ,i5,3(1pe11.3)) 910 format(1h ,'Newton iteration',i5) end subroutine wtchdg ( iter, wmerit, wmbest, wmprev, * itwtch, alfold, iflag ) * Logic for watchdog tests. implicit double precision (a-h,o-z) parameter ( itonew = 5, itwtmx = 8, grfct = 100.0d+0 ) parameter ( half = 0.5d+0 ) * Perform watchdog tests in two forms: * (1) to determine whether a sufficient decrease in the * watchdog merit function has occurred within the most recent * sequence of itwtmx iterations; * (2) to determine whether the watchdog merit function has increased * too much in a single iteration after itonew Newton iterations * have been performed. This allows the merit function to increase * wildly only during the first itonew iterations. * wmbest is the smallest watchdog merit function achieved in this * sequence of Newton iterations. * wmprev is the watchdog merit function from the immediately * preceding Newton iteration. * itwtch counts the number of iterations without an improvement * in the unscaled merit function. * write(6,99) iter, wmerit, wmbest, wmprev * write(6,98) itwtch, alfold * 99 format(1h ,'iter,wmer,wbest,wprev',i5,3(1pe15.5)) * 98 format(1h ,'itwtch,alfold',i5,1pe15.5) iflag = 0 if (wmerit .le. wmbest) then * The current watchdog merit function is the best. wmbest = wmerit itwtch = 0 return endif * The current merit function is not the best. itwtch = itwtch + 1 * Do not apply watchdog tests if (1) the previous step alfold * exceeds 1/2, or (2) the watchdog merit function decreased in * the immediately preceding iteration and itwtch does not * exceed twice its maximum. if (alfold .ge. half) return if (wmerit .le. wmprev .and. itwtch .le. 2*itwtmx) return * If more than itwtmx iterations have occurred without * an overall improvement in the watchdog merit function, * signal for termination. if (itwtch .ge. itwtmx) then iflag = -1 * If a too-large increase in the watchdog merit function * compared to the best value occurred, and iter .ge. itonew, * signal for termination. elseif (iter .ge. itonew .and. * wmerit .gt. grfct*wmbest) then iflag = -1 endif return end subroutine fneval(ncomp, nmsh, xx, nudim, u, fval, fsub) implicit double precision (a-h,o-z) dimension xx(nmsh), u(nudim,nmsh), fval(ncomp,nmsh) external fsub * fneval evaluates the function values (from fsub) for * a given mesh xx and array u, and stores the values * in the array fval. call fsub (ncomp, xx(1), u(1,1), fval(1,1)) do 50 im = 1, nmsh-1 hmsh = xx(im+1) - xx(im) call fsub (ncomp, xx(im+1), u(1,im+1), fval(1,im+1)) 50 continue return end subroutine jaccal (ncomp, nmsh, nlbc, * xx, nudim, u, fval, * dgtm, dftm1, dftm2, uint, * ajac, topblk, botblk, bhold, chold, * dfsub, dgsub) implicit double precision (a-h,o-z) dimension xx(nmsh), u(nudim,nmsh), fval(ncomp,nmsh) dimension dgtm(ncomp) dimension dftm1(ncomp, ncomp), dftm2(ncomp, ncomp), * uint(ncomp) dimension ajac(ncomp, 2*ncomp, nmsh-1) dimension topblk(nlbc, ncomp), botblk(ncomp-nlbc,ncomp) dimension bhold(ncomp, ncomp, nmsh-1), * chold(ncomp, ncomp, nmsh-1) external dfsub, dgsub logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 * blas: dcopy, ddot parameter ( zero = 0.0d+0, half = 0.5d+0, eighth = 0.125d+0 ) parameter ( four = 4.0d+0, six = 6.0d+0 ) parameter ( one = 1.0d+0, three = 3.0d+0, twelve = 12.0d+0 ) * if (pdebug) write(6,901) ninter = nmsh - 1 * if (pdebug) write(6,902) do 110 i = 1, nlbc call dgsub (i, ncomp, u(1,1), dgtm) call dcopy(ncomp, dgtm(1), 1, topblk(i,1), nlbc) * if (pdebug) write(6,903) i, (topblk(i,j),j=1,ncomp) 110 continue call dfsub (ncomp, xx(1), u(1,1), dftm1(1,1)) * on entry to jaccal, the array fval contains the function values * at (xx(im), u(ic,im)), ic=1,...,ncomp and im = 1,...,nmsh, * calculated by a preceding call of rhscal with the same xx and u * arrays. * if (pdebug) write(6,904) do 200 im = 1, ninter hmsh = xx(im+1) - xx(im) do 120 ic = 1, ncomp uint(ic) = half*(u(ic,im) + u(ic,im+1)) * - eighth*hmsh*(fval(ic,im+1) - fval(ic,im)) 120 continue xhalf = half*(xx(im+1) + xx(im)) call dfsub (ncomp, xhalf, uint, dftm2(1,1)) do 140 ic = 1, ncomp do 130 jc = 1, ncomp dsq = ddot(ncomp, dftm2(ic,1), ncomp, * dftm1(1,jc), 1) ajac(ic,jc,im) = -hmsh*(dftm1(ic,jc)/six * + dftm2(ic,jc)/three + hmsh*dsq/twelve) 130 continue ajac(ic,ic,im) = ajac(ic,ic,im) - one * if (pdebug) write(6,905) im, ic, * * (ajac(ic,jc,im), jc=1,ncomp) 140 continue call dfsub (ncomp, xx(im+1), u(1,im+1), dftm1(1,1)) do 170 ic = 1, ncomp do 160 jc = 1, ncomp dsq = ddot(ncomp, dftm2(ic,1), ncomp, * dftm1(1,jc), 1) ajac(ic,jc+ncomp,im) = -hmsh*(dftm1(ic,jc)/six * + dftm2(ic,jc)/three - hmsh*dsq/twelve) 160 continue call dcopy(ncomp, ajac(ic,ncomp+1,im), ncomp, * chold(ic,1,im), ncomp) call dcopy(ncomp, dftm1(ic,1), ncomp, * bhold(ic,1,im), ncomp) ajac(ic,ic+ncomp,im) = ajac(ic,ic+ncomp,im) + one chold(ic,ic,im) = ajac(ic,ic+ncomp,im) * if (pdebug) write(6,905) im, ic, * * (ajac(ic,jc+ncomp,im),jc=1,ncomp) 170 continue 200 continue * if (pdebug) write(6,906) do 220 i = nlbc+1, ncomp call dgsub (i, ncomp, u(1, nmsh), dgtm) call dcopy(ncomp, dgtm(1), 1, botblk(i-nlbc,1), ncomp-nlbc) * if (pdebug) write(6,903) i,(botblk(i-nlbc,j), j=1,ncomp) 220 continue c write(6,991) 991 format(1x,'topblk') c write(6,992) topblk(1,1),topblk(1,2) 992 format(1x,2g22.10) c write(6,993) 993 format(1x,'main jacobian') do 994 iu=1,ninter do 994 iv=1,ncomp c write(6,996) ajac(iv,1,iu),ajac(iv,2,iu),ajac(iv,3,iu), c +ajac(iv,4,iu) 996 format(1x,4f12.7) 994 continue c write(6,995) 995 format(1x,'botblk') c write(6,992) botblk(1,1),botblk(1,2) return 901 format(1h ,'jaccal') 902 format(1h ,'topblk') 903 format(1h ,i5,6(1pe11.3)) 904 format(1h ,'ajac') 905 format(1h ,2i5,5(1pe11.3)) 906 format(1h ,'botblk') end subroutine lnrhs (ncomp, nmsh, nlbc, * xx, nudim, u, fsub, gsub, * rhs, rnsq, fval, ftmp, uint) implicit double precision(a-h,o-z) * This subroutine is designed to calculate the right-hand * side for linear problems. dimension xx(*), u(nudim,*) dimension rhs(*), fval(ncomp,*), ftmp(*), uint(*) external fsub, gsub parameter ( zero = 0.0d+0, half = 0.5d+0, eighth = 0.125d+0 ) parameter ( one = 1.0d+0, four = 4.0d+0, six = 6.0d+0 ) common/mchprs/flmin, flmax, epsmch intrinsic abs * blas: dssq ninter = nmsh - 1 rnsq = zero * first, process the left-hand boundary conditions. do 20 i = 1, nlbc call gsub (i, ncomp, u(1,1), wg) rhs(i) = -wg 20 continue * Next, process the interior mesh points. The fval array * contains the function values from fsub at xx and u. do 50 im = 1, ninter hmsh = xx(im+1) - xx(im) do 30 ic = 1, ncomp uint(ic) = half*(u(ic,im) + u(ic,im+1)) * - eighth*hmsh*(fval(ic,im+1) - fval(ic,im)) 30 continue xhalf = half*(xx(im) + xx(im+1)) call fsub (ncomp, xhalf, uint, ftmp) loc = (im-1)*ncomp + nlbc do 40 ic = 1, ncomp rhs(loc+ic) = -u(ic,im+1) + u(ic,im) * + hmsh* * (fval(ic,im) + fval(ic,im+1) + four*ftmp(ic))/six 40 continue 50 continue nrhs = ninter*ncomp do 60 ii = nlbc+1, ncomp call gsub (ii, ncomp, u(1,nmsh), wg) rhs(nrhs+ii) = -wg 60 continue call dssq ( nmsh*ncomp, rhs, 1, scale, sumsq ) rnsq = (scale**2)*sumsq return end subroutine rhscal (ncomp, nmsh, nlbc, * xx, nudim, u, defcor, * fsub, gsub, * rhs, rnsq, fval, ftmp, uint) implicit double precision(a-h,o-z) * This subroutine constructs the (ncomp*nmsh)-dimensional * vector rhs, which is the right-hand side of the Newton equations. * The ncomp by nmsh array fval is assumed to have been calculated * elsewhere by routine fneval. dimension xx(nmsh), u(nudim,nmsh), defcor(ncomp,nmsh-1) dimension rhs(ncomp*nmsh), fval(ncomp,nmsh) dimension ftmp(ncomp), uint(ncomp) external fsub, gsub logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 common/mchprs/flmin, flmax, epsmch intrinsic abs * blas: dssq parameter ( zero = 0.0d+0, half = 0.5d+0, eighth = 0.125d+0 ) parameter ( one = 1.0d+0, four = 4.0d+0, six = 6.0d+0 ) * if (pdebug) write(6,901) * ninter is the number of intervals in the mesh (one less than the * number of mesh points) ninter = nmsh - 1 rnsq = zero * First, process the left-hand boundary conditions. do 20 i = 1, nlbc call gsub (i, ncomp, u(1,1), wg) rhs(i) = -wg 20 continue * Next, process the interior mesh points. The fval array * contains the function values from fsub at xx and u. do 50 im = 1, ninter hmsh = xx(im+1) - xx(im) do 30 ic = 1, ncomp uint(ic) = half*(u(ic,im) + u(ic,im+1)) * - eighth*hmsh*(fval(ic,im+1) - fval(ic,im)) 30 continue xhalf = half*(xx(im) + xx(im+1)) call fsub (ncomp, xhalf, uint, ftmp) loc = (im-1)*ncomp + nlbc do 40 ic = 1, ncomp rhs(loc+ic) = -u(ic,im+1) + u(ic,im) + defcor(ic,im) * + hmsh* * (fval(ic,im) + fval(ic,im+1) + four*ftmp(ic))/six 40 continue 50 continue nrhs = ninter*ncomp do 60 ii = nlbc+1, ncomp call gsub (ii, ncomp, u(1,nmsh), wg) rhs(nrhs+ii) = -wg 60 continue call dssq ( nmsh*ncomp, rhs, 1, scale, sumsq ) rnsq = (scale**2)*sumsq if (pdebug) then write (6,902) rnsq * write(6,903) * write(6,904) (rhs(i), i=1,ncomp*nmsh) endif return 901 format(1h ,'rhscal') 902 format(1h ,'rnsq',1pe11.3) 903 format(1h ,'rhs vector') 904 format(1h ,(7(1pe11.3))) end subroutine dblmsh (nmsh, nmax, xx, nmold, xxold, maxmsh) implicit double precision (a-h,o-z) dimension xx(*), xxold(*) logical maxmsh logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 * blas: dcopy parameter (half = 0.5d+0) * This routine is used to double the mesh, i.e., produce a mesh * with twice as many intervals in which each new interval is * half the corresponding old interval. * On entry to dblmsh, the integer nmsh and the array xx * specify a set of mesh points xx(1),..., xx(nmsh) (assumed * to be in ascending order). * If the number of mesh points in the doubled mesh would * exceed the maximum allowed number nmax, the flag maxmsh is * set to true, and we exit without changing any other parameters. * Otherwise, nmold is set to the old number of mesh points, * xxold is set to the old mesh, nmsh is the new number of mesh * points, and xx contains the new mesh points. nmold = nmsh call dcopy(nmold, xx, 1, xxold, 1) ninnew = 2*(nmsh-1) nmnew = ninnew + 1 if(nmnew .ge. nmax) then if (iprint .ge. 0) write(6,901) nmnew maxmsh = .true. return endif maxmsh = .false. * Loop backwards through the old mesh points to create the new ones. xx(nmnew) = xx(nmsh) do 100 i = ninnew, 4, -2 id2 = i/2 xx(i) = half*(xx(i+1) + xx(id2)) xx(i-1) = xx(id2) 100 continue * Calculate the new xx(2). xx(1) remains unchanged. xx(2) = half*(xx(3) + xx(1)) nmsh = nmnew if(iprint .ge. 0) write(6,902) nmsh return 901 format (1h , ' dblmsh. maximum mesh exceeded, nmnew =', i8) 902 format (1h , ' dblmsh. the doubled mesh has ', i8,' points.') end subroutine selmsh(ncomp, nmsh, ntol, ltol, tol, * nfxpnt, fixpnt, ipow, nmax, * xx, nudim, u, ermeas, irefin, ihcomp, * nmold, xxold, ermx, double, maxmsh) implicit double precision (a-h,o-z) dimension ltol(ntol), tol(ntol), fixpnt(*) dimension xx(*), u(nudim, *), ermeas(ncomp,*) dimension irefin(nmsh-1), ihcomp(nmsh-1) dimension xxold(*), ermx(*) logical double, maxmsh intrinsic abs, max, int * blas: dcopy * double precision dlog logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 parameter ( zero = 0.0d+0, one = 1.0d+0, onep1 = 1.1d+0 ) parameter ( erdcid = 5.0d+0 ) parameter ( phitst = 0.1d+0 ) logical first save first, rlndec data first / .true. / * The routine selmsh performs selective mesh refinement, depending * on the error measure ermeas. if (first) then first = .false. rlndec = dlog(erdcid) endif maxmsh = .false. if (pdebug) write(6,901) nmsh, ipow frcpow = one/ipow double = .false. nmold = nmsh ninter = nmsh - 1 * Copy the current mesh into the xxold array. call dcopy(nmold, xx, 1, xxold, 1) ithres = 0 thres = one * On input, the array ermeas represents some error measure defined * over the components and mesh intervals (not mesh points). * It is normalized in the following loop with respect to the * tolerance array and the current solution. * The value errmax gives the maximum normalized error. errmax = zero do 120 im = 1, ninter ermx(im) = zero do 110 it = 1, ntol jcomp = ltol(it) denom = tol(it)*max(one, abs(u(jcomp,im))) ems = ermeas(jcomp,im) ermeas(jcomp,im) = abs(ems)/denom * if (pdebug .and. ermeas(jcomp,im) .ge. thres) * * write(6,902) im,jcomp,ems,ermeas(jcomp,im) err = ermeas(jcomp, im) if (err .ge. ermx(im)) then ermx(im) = err ihcomp(im) = jcomp endif 110 continue errmax = max(ermx(im), errmax) 120 continue if (pdebug) write(6,903) errmax if (errmax .gt. zero .and. errmax .le. erdcid) then * If errmax > 0 and .le. erdcid, find the smallest integer exponent ii * such that (erdcid**ii)*errmax > erdcid. if(errmax .gt. one) then ii = 1 decii = erdcid else ilg = -dlog(errmax)/rlndec ii = 2 + ilg decii = erdcid**ii endif * Multiply error measures by erdcid**ii. errmax = decii*errmax do 140 im = 1, ninter ermx(im) = decii*ermx(im) do 140 it = 1, ntol jcomp = ltol(it) ermeas(jcomp,im) = decii*ermeas(jcomp,im) 140 continue endif 200 continue * For each interval im, the integer irefin(im) is calculated * based on an equidistrbution procedure involving the * threshold value thres. If irefin(im) > 1, we add * points to interval im. If irefin(im) = 1, we check whether * point im can be removed from the mesh. * nmest is a lower bound on the number of points in the new mesh. * We do not know in advance how many points will be removed, * so nmest is computed by assuming all eligible points are removed. nmest = nmsh do 220 im = 1, ninter if (ermx(im).ge.thres) then irefin(im) = int(ermx(im)**frcpow) + 1 nmest = nmest + irefin(im) - 1 else irefin(im) = 1 nmest = nmest - 1 endif 220 continue * if (pdebug) write(6,904) nmest, (irefin(i), i=1,ninter) if (nmest .gt. nmax) then go to 360 elseif (nmest-1 .gt. 3*ninter) then call dblmsh (nmsh, nmax, xx, nmold, xxold, maxmsh) double = .true. return endif * It appears that we can perform the desired selective mesh * refinement. * Now begin running through the mesh, adding and possibly deleting * points as indicated by the irefin array. * The integer new is a count of the number of intervals in * the tentative mesh being generated by the refinement strategy. new = 1 * The first interval is treated as a special case, since xx(1) * always remains in the mesh, and cannot be a fixed point. rlen = xxold(2) - xx(1) slen = rlen if (irefin(1).gt.1) then dx = rlen/irefin(1) do 230 j = 2, irefin(1) new = new + 1 xx(new) = xx(1) + (j-1)*dx 230 continue endif * The fixed points specified by the fixpnt array cannot be * removed from the mesh. The value fxnext indicates the 'next' * fixed point. When no further fixed points remain to be processed * (or if nfxpnt = 0), fxnext is set to a value strictly larger than * the last mesh point, so that no mesh point can equal fxnext. * This way we need to compare only the values of xxold(i) * and fxnext. ifxcnt = 1 if (nfxpnt .eq. 0) then fxnext = onep1*abs(xxold(nmsh)) else fxnext = fixpnt(ifxcnt) endif * jtkout is a counter of the number of consecutive points that * have been removed from the mesh. jtkout = 0 do 330 im = 2, ninter rlold = rlen rlen = xxold(im+1) - xxold(im) * If xxold(im) is the next fixed point, it cannot be removed * and so we don't test its error estimates. if(xxold(im) .eq. fxnext) then ifxcnt = ifxcnt + 1 if(ifxcnt .gt. nfxpnt) then fxnext = onep1*abs(xxold(nmsh)) else fxnext = fixpnt(ifxcnt) endif elseif (irefin(im).eq.1) then * If xxold(im) is not a fixed point and irefin(im) = 1, we may wish * to remove point im from the mesh. * If we are considering removing points and jtkout = 0, this * is the first point in a possible consecutive set to be removed, * and we initialize phihat, which represents a maximum of * certain estimates. * If jtkout is not zero, previous points contiguous to this * point have been removed, and phihat retains its previous value. slen = slen + rlen if (jtkout .eq. 0) then ind1 = ihcomp(im-1) phihat = ermeas(ind1,im-1)/(rlold**ipow) endif phihat = max(phihat, * ermeas(ihcomp(im),im)/(rlen**ipow)) val1 = phihat*(slen**ipow) if (val1 .le. phitst * .and. jtkout .lt. 4) then * Increment the counter of removed points. * 'Remove' the mesh point xxold(im) by not including it. jtkout = jtkout+1 go to 330 endif * end of logic for irefin(im) = 1. endif jtkout = 0 new = new + 1 xx(new) = xxold(im) if (irefin(im) .gt. 1) then dx = rlen/irefin(im) do 300 j = 2, irefin(im) new = new + 1 xx(new) = xxold(im) + (j-1)*dx 300 continue endif slen = rlen if (new .gt. nmax) then * If the new mesh contains too many points, branch out of the * loop to try alternative strategies. go to 360 elseif (new .gt. 3*ninter) then * Here, the new mesh does not exceed the specified maximum, * but has more than 3 times as many intervals as the old mesh. * Try doubling the mesh if possible. call dcopy(nmsh, xxold, 1, xx, 1) call dblmsh (nmsh, nmax, xx, nmold, xxold, maxmsh) double = .true. return endif 330 continue * To end up here, we have processed the entire interval, * and have neither exceeded the specified maximum nor * exceeded three times the number of intervals in the old * mesh. The last mesh point remains unchanged. new = new + 1 xx(new) = xxold(nmsh) nmsh = new maxmsh = .false. if (iprint .ge. 0) write(6,905) nmsh return 360 continue * To reach here, the number of mesh points created at some stage * of the refinement process was larger than the maximum permitted * value nmax. * Check whether the mesh can safely be doubled. if ((2*nmsh-1) .lt. nmax) then * Double the mesh. call dblmsh (nmsh, nmax, xx, nmold, xxold, maxmsh) double = .true. * If the number of intervals is too large and the mesh cannot be * doubled, increase the threshold thres by a factor of erdcid and * try the selective refinement again. * If this happens three times without success or if thres exceeds * or is equal to errmax, stop. (In this case, we know already * that doubling the mesh produces too many points.) elseif (thres .lt. errmax .and. ithres .lt. 3) then ithres = ithres + 1 thres = erdcid*thres if(thres .gt. errmax) thres = errmax call dcopy(nmsh, xxold, 1, xx, 1) go to 200 else nmsh = 2*nmsh - 1 maxmsh = .true. endif return 901 format(1h ,'selmsh. nmsh, ipow =',2i5) 902 format(1h ,'im, jcomp, ermeas, normalized er',2i5,2(1pe11.3)) 903 format(1h ,'errmax',1pe11.3) 904 format(1h ,'nmest, irefin',(10i5)) 905 format(1h ,'selmsh. new nmsh =',i8) 910 format(1h ,'ihcomp',(10i5)) end subroutine smpmsh (nmsh, nmax, xx, intref, numadd, * nmold, xxold, maxmsh) implicit double precision (a-h,o-z) logical maxmsh dimension xx(*), xxold(*) logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 * blas: dcopy * The routine smpmsh performs simple mesh refinement by adding * points to one or three interval(s) in the region indicated * by the integer intref. * numadd gives the trial number of points to be added in each * interval. if (pdebug) write(6,901) nmold = nmsh call dcopy(nmold, xx, 1, xxold, 1) * numadd is altered if necessary so that it lies between 4 and 49 if(numadd .gt. 49) then numadd = 49 elseif (numadd .lt. 4) then numadd = 4 endif if (pdebug) write (6,902) nmsh, intref, numadd maxmsh = .false. if (intref .eq. 1) then * Add numadd points to the first interval if intref = 1. nmnew = nmsh + numadd if (nmnew .gt. nmax) then if (iprint .ge. 0) write(6,903) nmnew maxmsh = .true. return endif * Renumber the later points in reverse order. nint = numadd + 1 do 100 i = nmnew, numadd+2, -1 xx(i) = xx(i-numadd) 100 continue dx = (xx(2) - xx(1))/nint do 110 i = 2, nint xx(i) = xx(1) + (i-1)*dx 110 continue elseif (intref .eq. nmsh-1) then * Add numadd points to the last interval if intref = nmsh-1. nmnew = nmsh + numadd if (nmnew .gt. nmax) then if (iprint .ge. 0) write(6,903) nmnew maxmsh = .true. return endif nint = numadd + 1 dx = (xx(nmsh) - xx(nmsh-1))/nint xx(nmnew) = xx(nmsh) do 200 i = nmsh, nmnew-1 xx(i) = xx(nmsh-1) + (i-nmsh+1)*dx 200 continue else if (numadd .gt. 9) numadd = 9 * Here, intref lies between 2 and nmsh-2. Add numadd points to * each of the three intervals intref-1, intref and intref+1. nmnew = nmsh + 3*numadd if (nmnew .gt. nmax) then if (iprint .ge. 0) write(6,903) nmnew maxmsh = .true. return endif * noalt is the number of points at the right end of the interval * whose numerical values remain the same, but whose indices change. * nochsm is the smallest index in the new ordering of one of these * points. noalt = nmsh - intref - 1 nochsm = nmnew - noalt + 1 * Renumber the noalt unchanged points at the right end of the interval * (in reverse order). j = 0 do 300 i = nmnew, nochsm, -1 xx(i) = xx(nmsh-j) j = j + 1 300 continue * Add numadd points to the three contiguous intervals. * The remaining points at the left end of the interval retain * their original indices, and are left unchanged. nint = numadd + 1 innew = nochsm - nint do 320 i = intref+1, intref-1, -1 xx(innew) = xx(i) dx = (xx(innew + nint) - xx(innew))/nint do 310 j = 1, numadd xx(innew + j) = xx(innew) + j*dx 310 continue innew = innew - nint 320 continue endif nmsh = nmnew if(iprint .ge. 0) write(6,904) nmsh return 901 format(1h , ' smpmsh') 902 format(1h ,'nmsh, intref, numadd',3i6) 903 format(1h , ' smpmsh. maximum points exceeded, nmnew =',i6) 904 format(1h ,'smpmsh, new nmsh =',i7) end subroutine unimsh(nmsh, aleft, aright, nfxpnt, fixpnt, xx) implicit double precision (a-h,o-z) integer nmsh, nfxpnt dimension fixpnt(*), xx(nmsh) logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 intrinsic max * Given a left endpoint aleft, a right endpoint aright, * a set of nfxpnt fixed points fixpnt(i), i = 1,...,nfxpnt, * (where fixpnt(i) is different from aleft and aright for all i), * and an initial target number nmsh of mesh points, * the subroutine unimsh generates a piecewise uniform mesh * beginning at aleft, ending at aright, and with equally * spaced points between aleft and fixpnt(1), then between * fixpnt(1) and fixpnt(2), ..., and finally between * fixpnt(nfxpnt) and aright. The final number of intervals * is the maximum of nfxpnt+2 and the initial value of nmsh. * In the simplest case when nfxpnt = 0, unimsh generates a * uniform mesh with nmsh intervals in the closed interval * (aleft, aright). * On exit, the integer nmsh contains the number of mesh points * (which is the maximum of the initial nmsh and nfxpnt). * The array xx (of dimension nmsh) contains the mesh points. if (iprint .ge. 0) write(6,901) nmsh if (nfxpnt .eq. 0) then * If there are no interior fixed points, the spacing is uniform * throughout the interval. Calculate the spacing dx * and set up the xx array. ninter = nmsh - 1 dx = (aright - aleft)/ninter do 10 i = 1, ninter xx(i) = aleft + (i-1)*dx 10 continue xx(nmsh) = aright return endif * We know that there is at least one fixed point strictly between * the endpoints. if (nmsh .lt. nfxpnt+2) nmsh = nfxpnt + 2 ninter = nmsh - 1 xx(1) = aleft ileft = 1 xleft = aleft totint = aright - aleft ndif = ninter - nfxpnt do 50 j = 1, nfxpnt + 1 * Deal in turn with the subintervals defined by the interval * boundaries and the fixed points. if (j .lt. nfxpnt+1) then * The j-th fixed point is xright. Calculate where it should * fall in the mesh. xright = fixpnt(j) nmin = ninter*(xright-aleft)/totint + 1.5d+0 if (nmin .gt. ndif+j) nmin = ndif + j iright = max(ileft+1, nmin) else xright = aright iright = nmsh endif * npt is the number of equally spaced points that should * lie strictly between the (j-1)-th and j-th fixed points. xx(iright) = xright npt = iright - ileft - 1 dx = (xright - xleft)/(npt + 1) do 30 i = 1, npt xx(ileft+i) = xleft + i*dx 30 continue ileft = iright xleft = xright 50 continue return c 901 format (1h ,'unimsh. nmsh =',i5) end subroutine stats(len, elem, ebigst, esecnd, summod, index) implicit double precision (a-h, o-z) integer index dimension elem(len) intrinsic abs parameter ( zero = 0.0d+0 ) * Given the real array elem of length len, stats calculates * the following: * - summod, the sum of the magnitudes of the elements of elem; * - ebigst (the largest element in magnitude); * - index (the index in elem of ebigst); and * - esecnd (the second largest element in magnitude, strictly * less than ebigst unless both are zero). index = 1 ebigst = zero esecnd = zero summod = zero do 100 i = 1, len elmod = abs(elem(i)) summod = summod + elmod if (elmod .gt. ebigst) then esecnd = ebigst ebigst = elmod index = i elseif (elmod .gt. esecnd) then esecnd = elmod endif 100 continue return end subroutine mshref(ncomp, nmsh, nlbc, ntol, ltol, * iorder, rhs, tmwork, * nmax, xx, nmold, xxold, double, maxmsh, * numbig, nummed) implicit double precision (a-h,o-z) dimension ltol(ntol) dimension rhs(ncomp*nmsh), tmwork(nmsh-1) dimension xx(nmsh), xxold(nmold) logical double, maxmsh logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 * blas: dcopy parameter (two = 2.0d+0) parameter (bigfac = 10.0d+0, small = 1.0d-2, numpt = 14) * This routine performs calculations leading to a decision * about how the mesh will be refined, and then refines the mesh. * The choices for mesh refinement in this routine are either to * double the mesh (i.e., divide each existing interval in half), * or to add points to just a few intervals. * The decision is made based on two criteria: (1) the distribution * of magnitudes of components of rhs (broadly speaking, if * the maximum component of rhs is much larger than the * average, points are added near the corresponding interval), * and (2) the history of previous mesh refinements (if points * have been added to only a few intervals already, this strategy * is abandoned for the moment and the mesh is doubled). * The decision is indicated by setting the logical flag double * and (if double is .false.) the integer intref. * Setting double to .true. means that the mesh should be doubled * (i.e., the new mesh should contain twice as many intervals). * The integer intref indicates the region of the mesh where the * points should be added (see the routine smpmsh), and numadd * indicates how many points are to be added. * The integers nummed and numbig represent running totals, * used in deciding on the mesh refinement strategy. * If iorder = 4, meaning that we were just performing a Newton * iteration for a 4th order solution, check all elements of rhs. * If iorder .gt. 4, signalling that we were trying Newton * iterations for order 6 or 8, check only elements of rhs * corresponding to components for which a tolerance is specified. if (pdebug) write(6,901) nummed, numbig ninter = nmsh-1 nup = ncomp if (iorder .gt. 4) nup = ntol * Check the vector rhs for a non-negligible component * whose magnitude is significantly larger than the average. * (small defines negligible, and bigfac defines significantly larger.) do 50 ic = 1, nup icmp = ic if (iorder .gt. 4) icmp = ltol(ic) * For component icmp, examine the ninter elements of rhs not * corresponding to boundary conditions. * subroutine stats calculates rbigst and rsecnd (the first- and * second-largest elements of rhs in magnitude), and the index * intref of the interval in which the largest value occurs. * The value sumrhs is the sum of the magnitudes of the components * of rhs. indrhs = nlbc + ic * Copy the elements of rhs corresponding to interior mesh * points for component icmp into a single vector tmwork. call dcopy(ninter, rhs(indrhs), ncomp, tmwork, 1) call stats(ninter, tmwork, rbigst, rsecnd, * sumrhs, intref) tstval = bigfac*(sumrhs-rbigst)/ninter if (pdebug) write(6,902) ic, tstval, rbigst, rsecnd if (rbigst .ge. small .and. rbigst .ge. tstval) go to 100 50 continue * If we reach this point, no interval has a significantly larger * element than average. Set counters and double the mesh. numbig = 0 nummed = 0 double = .true. if (pdebug) write(6,903) call dblmsh(nmsh, nmax, xx, nmold, xxold, maxmsh) return * To reach statement 100, it must be true that for some component * icmp, rbigst is non-negligible and large relative to the * average. intref indicates the region to which points may be added. * If too many specialized refinements (adding a few points to * a small number of intervals) have been made, signal that * the mesh should be doubled. * Otherwise, increment counters and add numadd points as indicated. 100 continue if (rbigst .lt. two*rsecnd) nummed = nummed + 1 numadd = numpt numbig = numbig + 1 double = .false. if (rbigst .le. bigfac*rsecnd .or. numbig .gt. 8) then numbig = 0 nummed = nummed + 1 if (nummed .ge. 4 .and. iorder .eq. 4) then double = .true. nummed = 0 elseif (nummed .ge. 8 .and. iorder .gt. 4) then double = .true. nummed = 0 endif endif * Refine the mesh. if (pdebug) write(6,904) numbig, nummed if (double .and. pdebug) write(6,905) if (double) then call dblmsh (nmsh, nmax, xx, nmold, xxold, maxmsh) else numadd = numpt call smpmsh (nmsh, nmax, xx, intref, numadd, * nmold, xxold, maxmsh) endif return 901 format(1h ,'mshref. nummed, numbig =',2i5) 902 format(1h ,'ic, tst, bigst, second',i5, 3(1pe11.3)) 903 format(1h ,'No significantly large value') 904 format(1h ,'numbig, nummed =',2i5) 905 format(1h ,'double the mesh') end subroutine errest (ncomp, nmsh, ntol, ltol, tol, * nudim, u, uold, etest, errsum, errok) implicit double precision (a-h,o-z) dimension ltol(ntol), tol(ntol), u(nudim,nmsh), * uold(ncomp,nmsh), etest(ntol) logical errok logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 intrinsic abs, max parameter ( one = 1.0d+0, zero = 0.0d+0 ) * Given current and previous solutions u and uold on the same * mesh, errest calculates an error measure for each * component for which a tolerance is specified. * The error measure is the usual relative error normalized * by dividing by the tolerance. On exit, errsum is the * sum of these error measures. * The array etest specifies the error test to be applied to each * error measure. * On exit, the logical flag errok * -- is .false. if any of the error measures exceeds the * corresponding value in the array etest * -- is .true. if all error measures are less than the * corresponding values of etest. if (pdebug) write(6,900) errsum = zero errok = .true. do 10 im = 1, nmsh do 10 it = 1, ntol icmp = ltol(it) er = u(icmp,im) - uold(icmp,im) denom = max(one, abs(uold(icmp,im))) errel = abs(er/(tol(it)*denom)) * if (pdebug) write(6,901) im, it, errel, etest(it) errsum = errsum + errel if (errel .gt. etest(it)) errok = .false. 10 continue if (pdebug) write(6,902) errsum return 900 format(1h ,'errest') 901 format(1h ,2i5,2(1pe11.3)) 902 format(1h ,'errsum',1pe11.3) end subroutine getptq( debug, mfsrch, nout, alfmax, alfsml, alfuzz, * epsaf, epsag, eta, ftry, oldf, oldg, * rmu, tolabs, tolrel, toltny, imprvd, * inform, nfsrch, alfa, alfbst, fbest, * braktd, crampd, extrap,vset,wset,nsamea,nsameb, * a, b, fa, factor, fv, fw, xtry, xv, xw ) implicit double precision (a-h,o-z) logical debug, imprvd logical braktd, crampd, extrap, vset, wset integer mfsrch, nout, inform, nfsrch, nsamea, nsameb c c ********************************************************************* c getptq is a step-length algorithm for minimizing a function of one c variable. it will be called repeatedly by a search routine whose c purpose is to estimate a point alfa = alfbst that minimizes some c function f(alfa) over the closed interval (0, alfmax). c c getptq requires the function f(alfa) (but not its gradient) c to be evaluated at various points within the interval. new c step-length estimates are computed using quadratic interpolation with c safeguards. c c reverse communication is used to allow the calling program to c evaluate f. some of the parameters must be set or tested c by the calling program. the remainder would ordinarily be local c variables. c c c input parameters (relevant to the calling program) c -------------------------------------------------- c c debug specifies whether detailed output is wanted. c c inform must be nonzero on the first entry (e.g., -1). c it will be altered by getptq for later entries. c c mfsrch is an upper limit on the number of times getptq is c to be entered consecutively with inform = 0 c (following an initial entry with inform lt 0). c c nout is the file number to be used for printed output c if debug is true. c c alfa is the first estimate of the step length. alfa is c subsequently altered by getptq (see below). c c alfmax is the upper limit of the interval to be searched. c c alfsml is intended to prevent inefficiency when the optimum c step is very small, for cases where the calling c program would prefer to re-define f(alfa). alfsml is c allowed to be zero. early termination will occur if c getptq determines that the optimum step lies c somewhere in the interval (0, alfsml) (but not if c alfmax .le. alfsml). c c epsaf is an estimate of the absolute precision in the c computed values of f. c c eta controls the accuracy of the search. it must lie c in the range 0.0 le eta lt 1.0. decreasing c eta tends to increase the accuracy of the search. c c oldf is the value of f(0). c c oldg is an estimate of the gradient of f at alfa = 0. c it should be non-positive. c c rmu controls what is meant by a significant decrease in f. c the final f(alfbst) should lie on or below the line c l(alfa) = oldf + alfa*rmu*oldg. c rmu should be in the open interval (0, 0.5). c the value rmu = 1.0d-4 is good for most purposes. c c tolabs,tolrel define a function tol(alfa) = tolrel*alfa + tolabs c such that if f has already been evaluated at step c alfa, then it will not be evaluated at any point c closer than tol(alfa). c these values may be reduced by getptq if they seem c to be too large. c c toltny is the smallest value that tolabs is allowed to be c reduced to. c c c output parameters (relevant to the calling program) c --------------------------------------------------- c c imprvd is true if the previous step alfa was the best c point so far. any related quantities (e.g., arrays) c should be saved by the calling program before paying c attention to inform. c c inform = 0 means the calling program should evaluate c ftry = f(alfa) c for the new trial step alfa, and then re-enter c getptq. c c inform = 1 means the search has terminated successfully c with a step alfbst that is less than the c upper bound alfmax. c c inform = 2 means the search has terminated successfully c with a step alfbst that is equal to the c upper bound alfmax. c c inform = 3 means that the search failed to find a point of c sufficient decrease in mfsrch functions, but an c improved point was found. c c inform = 4 means alfmax is so small that a search should c not have been done. c c inform = 5 means that the search was terminated prematurely c because of the value of alfsml (see above). c c inform = 6 means the search has failed to find a useful step. if c the subroutine for the function and gradient has been c programmed correctly, this will usually occur if the c minimum lies very close to alfa = 0 or the gradient c is not sufficiently accurate. c c inform = 7 means that the value of g(0) was positive on entry. c c alfa is the step at which the next function value must be c computed. c c alfbst should be accepted by the calling program as the c required step-length estimate, whenever getptq c returns inform = 1, 2 or 3. c c fbest will be the corresponding value of f. c c c the following parameters retain information between entries c ----------------------------------------------------------- c c alfuzz is such that, if the final alfa lies in the interval c (0,alfuzz) and abs( f(alfa)-oldf ) le epsaf, alfa c cannot be guaranteed to be a point of sufficient c decrease. c c braktd is false if f has not been evaluated at the far end c of the interval of uncertainty. in this case, the c point b will be at alfmax + tol(alfmax). c c crampd is true if alfmax is very small (le tolabs). c if the search fails, this indicates that a zero c step should be taken. c c extrap is true if alfbst has moved at least once and xv c lies outside the interval of uncertainty. in this c case, extra safeguards are applied to allow for c instability in the polynomial fit. c c vset records whether a third-best point has been c determined. c c wset records whether a second-best point has been c determined. it will always be true by the c time the convergence test is applied (label 300). c c nsamea is the number of consecutive times that the left-hand c end of the interval of uncertainty has remained the c same. c c nsameb similarly for the right-hand end. c c a, b, alfbst define the current interval of uncertainty. c the required minimum lies somewhere within the c closed interval (alfbst + a, alfbst + b). c c alfbst is the best point so far. it is strictly within the c the interval of uncertainty except when it lies at the c left-hand end when alfbst has not been moved. c hence we have a le 0, b gt 0. c c fbest is the value of f at the point alfbst. c c fa is the value of f at the point alfbst + a. c c factor controls the rate at which extrapolated estimates of c alfa may expand into the interval of uncertainty. c factor is not used if the minimum has been bracketed c (i.e., when the variable braktd is true). c c fv, fw are the values of f at the points alfbst + xv, c alfbst + xw. they are not defined until vset c or wset (respectively) is true. c c ftry is the value of f at the new point alfbst + xtry. c c xtry is the trial point within the shifted interval (a, b). c the new trial function value must be computed at the c point alfa = alfbst + xtry. c c xv is such that alfbst + xv is the third-best point. c it is not defined until vset is true. c c xw is such that alfbst + xw is the second-best point. c it is not defined until wset is true. c in some cases, xw will replace a previous xw that c has a lower function but has just been excluded from c the interval of uncertainty. c c c systems optimization laboratory, stanford university, california. c original version february 1982. rev. may 1983. c ********************************************************************* c logical closef, conv1, conv2, conv3, convrg logical moved, sigdec, xinxw data zero, point1, half/ 0.0d+0, 0.1d+0, 0.5d+0/ data one, two, five / 1.0d+0, 2.0d+0, 5.0d+0/ data ten, eleven /10.0d+0, 11.0d+0 / c c c local variables c --------------- c c closef is true if the worst function fv is within epsaf c of fbest (up or down). c c convrg will be set to true if at least one of the convergence c conditions holds at alfbst. c c moved is true if a better point has been found (alfbst gt 0). c c sigdec says whether fbest represents a significant decrease c in the function, compared to the initial value oldf. c c xinxw is true if xtry is in (xw,0) or (0,xw). c --------------------------------------------------------------------- c imprvd = .false. if (inform .ne. -1) go to 100 c c --------------------------------------------------------------------- c first entry. initialize various quantities, check input data and c prepare to evaluate the function at the initial step alfa. c --------------------------------------------------------------------- nfsrch = 0 alfbst = zero fbest = oldf if (oldg .gt. zero) go to 970 if (oldg .ge. (- epsag)) go to 960 if (alfmax .le. toltny) go to 940 c braktd = .false. crampd = alfmax .le. tolabs extrap = .false. vset = .false. wset = .false. nsamea = 0 nsameb = 0 alfuzz = two*epsaf/(rmu*abs( oldg )) a = zero b = alfmax + (tolrel*alfmax + tolabs) fa = oldf factor = five tol = tolabs xtry = alfa if (debug) write (nout, 1000) alfmax, oldf, oldg, tolabs, * alfuzz, epsaf, epsag, tolrel, crampd go to 800 c c --------------------------------------------------------------------- c subsequent entries. c the function has just been evaluated at alfa = alfbst + xtry, c giving ftry. c --------------------------------------------------------------------- 100 nsamea = nsamea + 1 nsameb = nsameb + 1 xtry = alfa - alfbst moved = alfbst .gt. zero c c check if xtry is in the interval (xw,0) or (0,xw). c xinxw = .false. if (wset) xinxw = zero .lt. xtry .and. xtry .le. xw * .or. xw .le. xtry .and. xtry .lt. zero c c see if the new step is better. c deltaf = ftry - oldf ctry = deltaf - alfa*rmu*oldg if (alfa .le. alfuzz) sigdec = deltaf .le. (- epsaf) if (alfa .gt. alfuzz) sigdec = ctry .le. epsaf imprvd = sigdec .and. ( ftry - fbest ) .le. (- epsaf) c if (debug) write (nout, 1100) alfa, ftry, ctry if (.not. imprvd) go to 130 c c we seem to have an improvement. the new point becomes the c origin and other points are shifted accordingly. c if (.not. wset) go to 110 xv = xw - xtry fv = fw vset = .true. 110 xw = zero - xtry fw = fbest wset = .true. fbest = ftry alfbst = alfa a = a - xtry b = b - xtry moved = .true. extrap = .not. xinxw c c decrease the length of the interval of uncertainty. c if (xtry .lt. zero) go to 120 a = xw fa = fw nsamea = 0 go to 300 120 b = xw nsameb = 0 braktd = .true. go to 300 c c the new function value is no better than the best point found so far. c the point xtry must be a new end point of the interval of c uncertainty. c 130 if (xtry .ge. zero) go to 140 a = xtry fa = ftry nsamea = 0 go to 150 140 b = xtry nsameb = 0 braktd = .true. c c the origin remains unchanged but xtry may qualify as xw. c 150 if (.not. wset) go to 160 if ((ftry - fw) .gt. epsaf) go to 170 xv = xw fv = fw vset = .true. 160 xw = xtry fw = ftry wset = .true. if (moved) extrap = xinxw go to 300 c c ftry is no better than fbest or fw. if the best point has not c been moved, there must be more than one minimum. c 170 if (moved) go to 175 xw = xtry fw = ftry go to 300 c c ftry is no better than fbest or fw, but xtry may become xv. c extrap has the value set in the previous entry. c 175 if (.not. vset) go to 180 if ((ftry - fv) .gt. epsaf .and. extrap) go to 300 180 if (xinxw) go to 190 xv = xtry fv = ftry vset = .true. go to 300 190 if (vset) xw = xv if (vset) fw = fv xv = xtry fv = ftry vset = .true. c c --------------------------------------------------------------------- c check the termination criteria. c --------------------------------------------------------------------- 300 tol = tolrel*alfbst + tolabs deltaf = fbest - oldf cbest = deltaf - alfbst*rmu*oldg if (alfbst .le. alfuzz) sigdec = deltaf .le. (- epsaf) if (alfbst .gt. alfuzz) sigdec = cbest .le. epsaf closef = .false. if (vset) closef = abs( fbest - fv ) .le. epsaf c conv1 = max( abs( a ), b ) .le. (tol + tol) * conv2 changed by mhw, 20 sept 1992, to allow it to be * satified for any significant decrease in f * conv2 = moved .and. sigdec * * .and. abs( fa - fbest ) .le. a*eta*oldg conv2 = moved .and. sigdec conv3 = closef .and. (sigdec .or. * (.not. moved) .and. (b .le. alfuzz)) convrg = conv1 .or. conv2 .or. conv3 c atrue = alfbst + a btrue = alfbst + b alfaw = alfbst + xw gap = b - a if (debug) write (nout, 1200) atrue, btrue, gap, tol, * nsamea, nsameb, braktd, closef, imprvd, conv1, conv2, conv3, * extrap, alfbst, fbest, cbest, alfaw, fw if (vset) alfav = alfbst + xv if (debug .and. vset) write (nout, 1300) alfav, fv if (convrg .and. moved) go to 910 c c exit if the step is too small. c if (btrue .lt. alfsml) go to 950 if (nfsrch .ge. mfsrch) go to 930 if (.not. convrg) go to 400 c c a better point has not yet been found (the step xw is no better c than step zero). check that the change in f is consistent with a c perturbation in x of tol, the estimate of the minimum spacing c constant. if the change in f is larger than epsaf, the value c of tol is reduced. c tol = xw/ten tolabs = tol if (abs(fw - oldf) .gt. epsaf .and. tol .gt. toltny) go to 400 if (crampd) go to 940 go to 960 c c --------------------------------------------------------------------- c proceed with the computation of a trial step length. c the choices are... c 1. parabolic fit using function values only. c 2. damped parabolic fit if the regular fit appears to be c consistently over-estimating the distance to the minimum. c 3. bisection, geometric bisection, or a step of tol if the c parabolic fit is unsatisfactory. c --------------------------------------------------------------------- 400 xmidpt = half*(a + b) q = zero s = zero c c --------------------------------------------------------------------- c fit a parabola. c --------------------------------------------------------------------- c c check if there are two or three points for the parabolic fit. c gw = (fw - fbest)/xw if (vset .and. moved) go to 450 c c only two points available. use fbest, fw and the derivative c oldg. c if (.not. moved) s = oldg if ( moved) s = oldg - two*gw q = two*(oldg - gw) if (debug) write (nout, 2100) go to 600 c c three points available. use fbest, fw and fv. c 450 gv = (fv - fbest)/xv s = gv - (xv/xw)*gw q = two*(gv - gw) if (debug) write (nout, 2200) c c --------------------------------------------------------------------- c construct an artificial interval (artifa, artifb) in which the c new estimate of the step length must lie. set a default value of c xtry that will be used if the polynomial fit is rejected. in the c following, the interval (a,b) is considered the sum of two c intervals of lengths dtry and daux, with common end point at the c best point (zero). dtry is the length of the interval into which c the default xtry will be placed and endpnt denotes its non-zero c end point. the magnitude of xtry is computed so that the exponents c of dtry and daux are approximately bisected. c --------------------------------------------------------------------- 600 artifa = a artifb = b if (braktd) go to 610 c c the minimum has not been bracketed. set an artificial upper bound c by expanding the interval xw by a suitable factor. c xtry = - factor*xw artifb = xtry if (alfbst + xtry .lt. alfmax) factor = five*factor go to 700 c c the minimum has been bracketed. c if the gradient at the origin is being used for the c polynomial fit, the default xtry is one tenth of xw. c 610 if (vset .and. moved) go to 620 xtry = xw/ten if (debug) write (nout, 2400) xtry go to 700 c c three points exist in the interval of uncertainty. check whether c the points are configured for an extrapolation or interpolation. c 620 if (extrap) go to 660 c c if the interpolation appears to be consistently over-estimating the c distance to the minimum, damp the interpolation step. c if (nsamea .lt. 3 .and. nsameb .lt. 3) go to 630 factor = factor / five s = factor * s go to 640 630 factor = one c c the points are configured for an interpolation. the artificial c interval will be just (a,b). set endpnt so that xtry c lies in the larger of the intervals (a,0) and (0,b). c 640 if (xmidpt .lt. zero) endpnt = a if (xmidpt .gt. zero) endpnt = b c c if a bound has remained the same for three iterations, set endpnt c so that xtry is likely to replace the offending bound. c if (nsamea .ge. 3) endpnt = a if (nsameb .ge. 3) endpnt = b go to 680 c c the points are configured for an extrapolation. c 660 if (xw .lt. zero) endpnt = b if (xw .gt. zero) endpnt = a c c compute the default value of xtry. c 680 dtry = abs( endpnt ) daux = gap - dtry if (daux .ge. dtry) xtry = five*dtry*(point1 + dtry/daux)/eleven if (daux .lt. dtry) xtry = half*sqrt( daux )*sqrt( dtry ) if (endpnt .lt. zero) xtry = - xtry if (debug) write (nout, 2500) xtry, daux, dtry c c if the points are configured for an extrapolation set the artificial c bounds so that the artificial interval lies strictly within (a,b). c if the polynomial fit is rejected, xtry will remain at the relevant c artificial bound. c if (extrap .and. xtry .le. zero) artifa = xtry if (extrap .and. xtry .gt. zero) artifb = xtry c c --------------------------------------------------------------------- c the polynomial fits give (s/q)*xw as the new step. c reject this step if it lies outside (artifa, artifb). c --------------------------------------------------------------------- 700 if (q .eq. zero) go to 800 if (q .lt. zero) s = - s if (q .lt. zero) q = - q if (s*xw .lt. q*artifa .or. s*xw .gt. q*artifb) go to 800 c c accept the polynomial fit. c xtry = zero if (abs( s*xw ) .ge. q*tol) xtry = (s/q)*xw if (debug) write (nout, 2600) xtry c c --------------------------------------------------------------------- c test for xtry being larger than alfmax or too close to a or b. c --------------------------------------------------------------------- 800 if (braktd) go to 810 c c if the step is close to or larger than alfmax, replace it by c alfmax (to force evaluation of the function at the boundary). c alfa = alfbst + xtry if (alfmax - alfa .gt. (tolrel*alfmax + tolabs)) go to 810 braktd = .true. xtry = alfmax - alfbst alfa = alfmax go to 900 c c otherwise, the function must not be evaluated at a point too close c to a or b. (it has already been evaluated at both those points.) c 810 xmidpt = half*(a + b) if (xtry .gt. a + tol .and. xtry .lt. b - tol) go to 820 if (xmidpt .gt. zero) xtry = tol if (xmidpt .le. zero) xtry = - tol c c c f must not be calculated too close to alfbst. c 820 if (abs( xtry ) .lt. tol .and. xmidpt .lt. zero) xtry = - tol if (abs( xtry ) .lt. tol .and. xmidpt .ge. zero) xtry = tol alfa = alfbst + xtry c c --------------------------------------------------------------------- c exit. c --------------------------------------------------------------------- c c new function value required. c 900 inform = 0 go to 990 c c convergence test satisfied. c 910 inform = 1 if (alfa .eq. alfmax) inform = 2 go to 990 c c mfsrch function evaluations without sufficient decrease, but an c improved point was found. c 930 if (.not. moved) go to 960 inform = 3 go to 990 c c zero step (alfmax too small). c 940 inform = 4 go to 990 c c premature termination. the step is smaller than alfsml. c 950 inform = 5 go to 990 c c zero step (a sufficiently better point could not be found). c 960 inform = 6 go to 990 c c zero step (positive gradient at the starting point). c 970 inform = 7 c c exit. c 990 if (debug) write (nout, 3000) return c 1000 format(/ 31h alfmax oldf oldg tolabs, 1p2e22.14, 1p2e16.8 * / 31h alfuzz epsaf epsag tolrel, 1p2e22.14, 1p2e16.8 * / 31h crampd , l6) 1100 format(/ 31h alfa ftry ctry , 1p2e22.14, 1pe16.8) 1200 format(/ 31h a b b - a tol , 1p2e22.14, 1p2e16.8 * / 31h nsamea nsameb braktd closef, 2i3, 2l6 * / 31h imprvd convrg extrap , l6, 3x, 3l1, l6 * / 31h alfbst fbest cbest , 1p2e22.14, 1pe16.8 * / 31h alfaw fw , 1p2e22.14) 1300 format( 31h alfav fv , 1p2e22.14 /) 2100 format(30h parabolic fit, two points.) 2200 format(30h parabolic fit, three points.) 2400 format(31h exponent reduced. trial point, 1p1e22.14) 2500 format(31h geo. bisection. xtry,daux,dtry, 1p3e22.14) 2600 format(31h polynomial fit accepted. xtry, 1p1e22.14) 3000 format(53h ---------------------------------------------------- /) c c end of getptq end subroutine interp(ncomp, nmsh, xx, nudim, u, * nmold, xxold, uold) implicit double precision (a-h, o-z) dimension xx(*), u(nudim,*), xxold(*), uold(ncomp,*) logical pdebug common/algprs/ nminit, pdebug, iprint, idum, uval0 * blas: dcopy parameter (zero = 0.0d+0) * interp performs piecewise linear interpolation of the old * solution uold at the nmold old mesh points xxold onto the nmsh * new mesh points xx, producing an interpolated solution u. * Note that no assumption is made that the new mesh has * more points than the old, nor that the new and old mesh * points are related in a specific way (except that their first * and last points are identical). if (pdebug) write(6,900) * By construction, xx(1) = xxold(1). Copy the first ncomp * components of uold into those of u. call dcopy(ncomp, uold(1,1), 1, u(1,1), 1) i = 2 do 100 im = 2, nmsh-1 50 continue if (i .gt. nmold) return * Check whether the im-th point in the new mesh lies strictly * to the right of, or to the left of (or exactly on) the * i-th point in the old mesh. if (xx(im) .gt. xxold(i)) then i = i + 1 go to 50 else xdif = xxold(i) - xx(im) if (xdif .eq. zero) then * xx(im) and xxold(i) are identical. call dcopy(ncomp, uold(1,i), 1, u(1,im), 1) i = i + 1 else xint = xxold(i) - xxold(i-1) xrat = xdif/xint do 70 k = 1, ncomp u(k,im) = uold(k,i) + xrat*(uold(k,i-1)-uold(k,i)) 70 continue endif endif 100 continue call dcopy(ncomp, uold(1,nmold), 1, u(1,nmsh), 1) return 900 format(1h ,'interp') end subroutine rerrvl( ncomp, nmsh, nudim, u, usvrex, ntol, ltol, * rerr, remax, itlmx, adjrer ) implicit double precision (a-h,o-z) dimension ltol(*) dimension u(nudim, *), usvrex(ncomp, *) dimension rerr(ncomp, *) logical adjrer intrinsic abs, max parameter ( one = 1.0d+0, zero = 0.0d+0 ) * rerrvl is used in considering Richardson extrapolation. * The two solutions u and usvrex have a special relationship: * u corresponds to a doubled mesh, with twice as many * intervals, where each interval is half the size of that for * usvrex's mesh. nmsh is the number of mesh points in the * mesh for u. * remax is the maximum relative error, and itlmx is the * index of the tolerance for which the maximum occurs. * The array rerr contains the absolute value of the difference * between u and usvrex at the common mesh points, but is defined * only for components for which an error tolerance is specified. * The logical variable adjrer is true on entry if the values in * rerr are to be adjusted for later use in selective mesh refinement. itlmx = 1 remax = zero nmold = 1 + (nmsh-1)/2 do 100 it = 1, ntol icmp = ltol(it) imnew = 1 do 50 im = 1, nmold rerr(icmp, im) = abs(usvrex(icmp,im) - u(icmp,imnew)) denom = max(one, abs(usvrex(icmp,im))) rerel = rerr(icmp,im)/denom if (rerel .gt. remax) then remax = rerel itlmx = it endif imnew = imnew + 2 50 continue 100 continue if (adjrer) then * Adjust the rerr array if it may be used later in selective * mesh refinement. do 150 it = 1, ntol icmp = ltol(it) do 150 im = 1, nmold - 1 rerr(icmp,im) = max(rerr(icmp,im), * rerr(icmp, im+1)) 150 continue endif return end