subroutine stoda (neq, y, yh, nyh, yh1, ewt, savf, acor, 1 wm, iwm, f, jac, pjac, slvs) clll. optimize external f, jac, pjac, slvs integer neq, nyh, iwm integer iownd, ialth, ipup, lmax, meo, nqnyh, nslp, 1 icf, ierpj, iersl, jcur, jstart, kflag, l, meth, miter, 2 maxord, maxcor, msbp, mxncf, n, nq, nst, nfe, nje, nqu integer iownd2, icount, irflag, jtyp, mused, mxordn, mxords integer i, i1, iredo, iret, j, jb, m, ncf, newq integer lm1, lm1p1, lm2, lm2p1, nqm1, nqm2 double precision y, yh, yh1, ewt, savf, acor, wm double precision rownd, 1 conit, crate, el, elco, hold, rmax, tesco, 2 ccmax, el0, h, hmin, hmxi, hu, rc, tn, uround double precision rownd2, pdest, pdlast, ratio, cm1, cm2, 1 pdnorm double precision dcon, ddn, del, delp, dsm, dup, exdn, exsm, exup, 1 r, rh, rhdn, rhsm, rhup, told, vmnorm double precision alpha, dm1, dm2, exm1, exm2, pdh, pnorm, rate, 1 rh1, rh1it, rh2, rm, sm1 dimension neq(1), y(1), yh(nyh,1), yh1(1), ewt(1), savf(1), 1 acor(1), wm(1), iwm(1) dimension sm1(12) common /ls0001/ rownd, conit, crate, el(13), elco(13,12), 1 hold, rmax, tesco(3,12), 2 ccmax, el0, h, hmin, hmxi, hu, rc, tn, uround, iownd(14), 3 ialth, ipup, lmax, meo, nqnyh, nslp, 4 icf, ierpj, iersl, jcur, jstart, kflag, l, meth, miter, 5 maxord, maxcor, msbp, mxncf, n, nq, nst, nfe, nje, nqu common /lsa001/ rownd2, pdest, pdlast, ratio, cm1(12), cm2(5), 1 pdnorm, 2 iownd2(3), icount, irflag, jtyp, mused, mxordn, mxords data sm1/0.5d0, 0.575d0, 0.55d0, 0.45d0, 0.35d0, 0.25d0, 1 0.20d0, 0.15d0, 0.10d0, 0.075d0, 0.050d0, 0.025d0/ c----------------------------------------------------------------------- c stoda performs one step of the integration of an initial value c problem for a system of ordinary differential equations. c note.. stoda is independent of the value of the iteration method c indicator miter, when this is .ne. 0, and hence is independent c of the type of chord method used, or the jacobian structure. c communication with stoda is done with the following variables.. c c y = an array of length .ge. n used as the y argument in c all calls to f and jac. c neq = integer array containing problem size in neq(1), and c passed as the neq argument in all calls to f and jac. c yh = an nyh by lmax array containing the dependent variables c and their approximate scaled derivatives, where c lmax = maxord + 1. yh(i,j+1) contains the approximate c j-th derivative of y(i), scaled by h**j/factorial(j) c (j = 0,1,...,nq). on entry for the first step, the first c two columns of yh must be set from the initial values. c nyh = a constant integer .ge. n, the first dimension of yh. c yh1 = a one-dimensional array occupying the same space as yh. c ewt = an array of length n containing multiplicative weights c for local error measurements. local errors in y(i) are c compared to 1.0/ewt(i) in various error tests. c savf = an array of working storage, of length n. c acor = a work array of length n, used for the accumulated c corrections. on a successful return, acor(i) contains c the estimated one-step local error in y(i). c wm,iwm = real and integer work arrays associated with matrix c operations in chord iteration (miter .ne. 0). c pjac = name of routine to evaluate and preprocess jacobian matrix c and p = i - h*el0*jac, if a chord method is being used. c it also returns an estimate of norm(jac) in pdnorm. c slvs = name of routine to solve linear system in chord iteration. c ccmax = maximum relative change in h*el0 before pjac is called. c h = the step size to be attempted on the next step. c h is altered by the error control algorithm during the c problem. h can be either positive or negative, but its c sign must remain constant throughout the problem. c hmin = the minimum absolute value of the step size h to be used. c hmxi = inverse of the maximum absolute value of h to be used. c hmxi = 0.0 is allowed and corresponds to an infinite hmax. c hmin and hmxi may be changed at any time, but will not c take effect until the next change of h is considered. c tn = the independent variable. tn is updated on each step taken. c jstart = an integer used for input only, with the following c values and meanings.. c 0 perform the first step. c .gt.0 take a new step continuing from the last. c -1 take the next step with a new value of h, c n, meth, miter, and/or matrix parameters. c -2 take the next step with a new value of h, c but with other inputs unchanged. c on return, jstart is set to 1 to facilitate continuation. c kflag = a completion code with the following meanings.. c 0 the step was succesful. c -1 the requested error could not be achieved. c -2 corrector convergence could not be achieved. c -3 fatal error in pjac or slvs. c a return with kflag = -1 or -2 means either c abs(h) = hmin or 10 consecutive failures occurred. c on a return with kflag negative, the values of tn and c the yh array are as of the beginning of the last c step, and h is the last step size attempted. c maxord = the maximum order of integration method to be allowed. c maxcor = the maximum number of corrector iterations allowed. c msbp = maximum number of steps between pjac calls (miter .gt. 0). c mxncf = maximum number of convergence failures allowed. c meth = current method. c meth = 1 means adams method (nonstiff) c meth = 2 means bdf method (stiff) c meth may be reset by stoda. c miter = corrector iteration method. c miter = 0 means functional iteration. c miter = jt .gt. 0 means a chord iteration corresponding c to jacobian type jt. (the lsoda argument jt is c communicated here as jtyp, but is not used in stoda c except to load miter following a method switch.) c miter may be reset by stoda. c n = the number of first-order differential equations. c----------------------------------------------------------------------- kflag = 0 told = tn ncf = 0 ierpj = 0 iersl = 0 jcur = 0 icf = 0 delp = 0.0d0 if (jstart .gt. 0) go to 200 if (jstart .eq. -1) go to 100 if (jstart .eq. -2) go to 160 c----------------------------------------------------------------------- c on the first call, the order is set to 1, and other variables are c initialized. rmax is the maximum ratio by which h can be increased c in a single step. it is initially 1.e4 to compensate for the small c initial h, but then is normally equal to 10. if a failure c occurs (in corrector convergence or error test), rmax is set at 2 c for the next increase. c cfode is called to get the needed coefficients for both methods. c----------------------------------------------------------------------- lmax = maxord + 1 nq = 1 l = 2 ialth = 2 rmax = 10000.0d0 rc = 0.0d0 el0 = 1.0d0 crate = 0.7d0 hold = h nslp = 0 ipup = miter iret = 3 c initialize switching parameters. meth = 1 is assumed initially. ----- icount = 20 irflag = 0 pdest = 0.0d0 pdlast = 0.0d0 ratio = 5.0d0 call cfode (2, elco, tesco) CVD$L NOCONCUR do 10 i = 1,5 10 cm2(i) = tesco(2,i)*elco(i+1,i) call cfode (1, elco, tesco) CVD$L NOVECTOR do 20 i = 1,12 20 cm1(i) = tesco(2,i)*elco(i+1,i) go to 150 c----------------------------------------------------------------------- c the following block handles preliminaries needed when jstart = -1. c ipup is set to miter to force a matrix update. c if an order increase is about to be considered (ialth = 1), c ialth is reset to 2 to postpone consideration one more step. c if the caller has changed meth, cfode is called to reset c the coefficients of the method. c if h is to be changed, yh must be rescaled. c if h or meth is being changed, ialth is reset to l = nq + 1 c to prevent further changes in h for that many steps. c----------------------------------------------------------------------- 100 ipup = miter lmax = maxord + 1 if (ialth .eq. 1) ialth = 2 if (meth .eq. mused) go to 160 call cfode (meth, elco, tesco) ialth = l iret = 1 c----------------------------------------------------------------------- c the el vector and related constants are reset c whenever the order nq is changed, or at the start of the problem. c----------------------------------------------------------------------- 150 do 155 i = 1,l 155 el(i) = elco(i,nq) nqnyh = nq*nyh rc = rc*el(1)/el0 el0 = el(1) conit = 0.5d0/dfloat(nq+2) go to (160, 170, 200), iret c----------------------------------------------------------------------- c if h is being changed, the h ratio rh is checked against c rmax, hmin, and hmxi, and the yh array rescaled. ialth is set to c l = nq + 1 to prevent a change of h for that many steps, unless c forced by a convergence or error test failure. c----------------------------------------------------------------------- 160 if (h .eq. hold) go to 200 rh = h/hold h = hold iredo = 3 go to 175 170 rh = dmax1(rh,hmin/dabs(h)) 175 rh = dmin1(rh,rmax) rh = rh/dmax1(1.0d0,dabs(h)*hmxi*rh) c----------------------------------------------------------------------- c if meth = 1, also restrict the new step size by the stability region. c if this reduces h, set irflag to 1 so that if there are roundoff c problems later, we can assume that is the cause of the trouble. c----------------------------------------------------------------------- if (meth .eq. 2) go to 178 irflag = 0 pdh = dmax1(dabs(h)*pdlast,0.000001d0) if (rh*pdh*1.00001d0 .lt. sm1(nq)) go to 178 rh = sm1(nq)/pdh irflag = 1 178 continue r = 1.0d0 do 180 j = 2,l c r = r*rh r = rh**(j-1) do 180 i = 1,n 180 yh(i,j) = yh(i,j)*r h = h*rh rc = rc*rh ialth = l if (iredo .eq. 0) go to 690 c----------------------------------------------------------------------- c this section computes the predicted values by effectively c multiplying the yh array by the pascal triangle matrix. c rc is the ratio of new to old values of the coefficient h*el(1). c when rc differs from 1 by more than ccmax, ipup is set to miter c to force pjac to be called, if a jacobian is involved. c in any case, pjac is called at least every msbp steps. c----------------------------------------------------------------------- 200 if (dabs(rc-1.0d0) .gt. ccmax) ipup = miter if (nst .ge. nslp+msbp) ipup = miter tn = tn + h i1 = nqnyh + 1 do 215 jb = 1,nq i1 = i1 - nyh cdir$ ivdep do 210 i = i1,nqnyh 210 yh1(i) = yh1(i) + yh1(i+nyh) 215 continue pnorm = vmnorm (n, yh1, ewt) c----------------------------------------------------------------------- c up to maxcor corrector iterations are taken. a convergence test is c made on the r.m.s. norm of each correction, weighted by the error c weight vector ewt. the sum of the corrections is accumulated in the c vector acor(i). the yh array is not altered in the corrector loop. c----------------------------------------------------------------------- 220 m = 0 rate = 0.0d0 del = 0.0d0 do 230 i = 1,n 230 y(i) = yh(i,1) call f (neq, tn, y, savf) nfe = nfe + 1 if (ipup .le. 0) go to 250 c----------------------------------------------------------------------- c if indicated, the matrix p = i - h*el(1)*j is reevaluated and c preprocessed before starting the corrector iteration. ipup is set c to 0 as an indicator that this has been done. c----------------------------------------------------------------------- ipup = 0 rc = 1.0d0 nslp = nst crate = 0.7d0 call pjac (neq, y, yh, nyh, ewt, acor, savf, wm, iwm, f, jac) if (ierpj .ne. 0) go to 430 250 do 260 i = 1,n 260 acor(i) = 0.0d0 270 if (miter .ne. 0) go to 350 c----------------------------------------------------------------------- c in the case of functional iteration, update y directly from c the result of the last function evaluation. c----------------------------------------------------------------------- do 290 i = 1,n savf(i) = h*savf(i) - yh(i,2) 290 y(i) = savf(i) - acor(i) del = vmnorm (n, y, ewt) do 300 i = 1,n y(i) = yh(i,1) + el(1)*savf(i) 300 acor(i) = savf(i) go to 400 c----------------------------------------------------------------------- c in the case of the chord method, compute the corrector error, c and solve the linear system with that as right-hand side and c p as coefficient matrix. c----------------------------------------------------------------------- 350 do 360 i = 1,n 360 y(i) = h*savf(i) - (yh(i,2) + acor(i)) call slvs (wm, iwm, y, savf) if (iersl .lt. 0) go to 430 if (iersl .gt. 0) go to 410 del = vmnorm (n, y, ewt) do 380 i = 1,n acor(i) = acor(i) + y(i) 380 y(i) = yh(i,1) + el(1)*acor(i) c----------------------------------------------------------------------- c test for convergence. if m.gt.0, an estimate of the convergence c rate constant is stored in crate, and this is used in the test. c c we first check for a change of iterates that is the size of c roundoff error. if this occurs, the iteration has converged, and a c new rate estimate is not formed. c in all other cases, force at least two iterations to estimate a c local lipschitz constant estimate for adams methods. c on convergence, form pdest = local maximum lipschitz constant c estimate. pdlast is the most recent nonzero estimate. c----------------------------------------------------------------------- 400 continue if (del .le. 100.0d0*pnorm*uround) go to 450 if (m .eq. 0 .and. meth .eq. 1) go to 405 if (m .eq. 0) go to 402 rm = 1024.0d0 if (del .le. 1024.0d0*delp) rm = del/delp rate = dmax1(rate,rm) crate = dmax1(0.2d0*crate,rm) 402 dcon = del*dmin1(1.0d0,1.5d0*crate)/(tesco(2,nq)*conit) if (dcon .gt. 1.0d0) go to 405 pdest = dmax1(pdest,rate/dabs(h*el(1))) if (pdest .ne. 0.0d0) pdlast = pdest go to 450 405 continue m = m + 1 if (m .eq. maxcor) go to 410 if (m .ge. 2 .and. del .gt. 2.0d0*delp) go to 410 delp = del call f (neq, tn, y, savf) nfe = nfe + 1 go to 270 c----------------------------------------------------------------------- c the corrector iteration failed to converge. c if miter .ne. 0 and the jacobian is out of date, pjac is called for c the next try. otherwise the yh array is retracted to its values c before prediction, and h is reduced, if possible. if h cannot be c reduced or mxncf failures have occurred, exit with kflag = -2. c----------------------------------------------------------------------- 410 if (miter .eq. 0 .or. jcur .eq. 1) go to 430 icf = 1 ipup = miter go to 220 430 icf = 2 ncf = ncf + 1 rmax = 2.0d0 tn = told i1 = nqnyh + 1 do 445 jb = 1,nq i1 = i1 - nyh cdir$ ivdep do 440 i = i1,nqnyh 440 yh1(i) = yh1(i) - yh1(i+nyh) 445 continue if (ierpj .lt. 0 .or. iersl .lt. 0) go to 680 if (dabs(h) .le. hmin*1.00001d0) go to 670 if (ncf .eq. mxncf) go to 670 rh = 0.25d0 ipup = miter iredo = 1 go to 170 c----------------------------------------------------------------------- c the corrector has converged. jcur is set to 0 c to signal that the jacobian involved may need updating later. c the local error test is made and control passes to statement 500 c if it fails. c----------------------------------------------------------------------- 450 jcur = 0 if (m .eq. 0) dsm = del/tesco(2,nq) if (m .gt. 0) dsm = vmnorm (n, acor, ewt)/tesco(2,nq) if (dsm .gt. 1.0d0) go to 500 c----------------------------------------------------------------------- c after a successful step, update the yh array. c decrease icount by 1, and if it is -1, consider switching methods. c if a method switch is made, reset various parameters, c rescale the yh array, and exit. if there is no switch, c consider changing h if ialth = 1. otherwise decrease ialth by 1. c if ialth is then 1 and nq .lt. maxord, then acor is saved for c use in a possible order increase on the next step. c if a change in h is considered, an increase or decrease in order c by one is considered also. a change in h is made only if it is by a c factor of at least 1.1. if not, ialth is set to 3 to prevent c testing for that many steps. c----------------------------------------------------------------------- kflag = 0 iredo = 0 nst = nst + 1 hu = h nqu = nq mused = meth do 460 j = 1,l do 460 i = 1,n 460 yh(i,j) = yh(i,j) + el(j)*acor(i) icount = icount - 1 if (icount .ge. 0) go to 488 if (meth .eq. 2) go to 480 c----------------------------------------------------------------------- c we are currently using an adams method. consider switching to bdf. c if the current order is greater than 5, assume the problem is c not stiff, and skip this section. c if the lipschitz constant and error estimate are not polluted c by roundoff, go to 470 and perform the usual test. c otherwise, switch to the bdf methods if the last step was c restricted to insure stability (irflag = 1), and stay with adams c method if not. when switching to bdf with polluted error estimates, c in the absence of other information, double the step size. c c when the estimates are ok, we make the usual test by computing c the step size we could have (ideally) used on this step, c with the current (adams) method, and also that for the bdf. c if nq .gt. mxords, we consider changing to order mxords on switching. c compare the two step sizes to decide whether to switch. c the step size advantage must be at least ratio = 5 to switch. c----------------------------------------------------------------------- if (nq .gt. 5) go to 488 if (dsm .gt. 100.0d0*pnorm*uround .and. pdest .ne. 0.0d0) 1 go to 470 if (irflag .eq. 0) go to 488 rh2 = 2.0d0 nqm2 = min0(nq,mxords) go to 478 470 continue exsm = 1.0d0/dfloat(l) rh1 = 1.0d0/(1.2d0*dsm**exsm + 0.0000012d0) rh1it = 2.0d0*rh1 pdh = pdlast*dabs(h) if (pdh*rh1 .gt. 0.00001d0) rh1it = sm1(nq)/pdh rh1 = dmin1(rh1,rh1it) if (nq .le. mxords) go to 474 nqm2 = mxords lm2 = mxords + 1 exm2 = 1.0d0/dfloat(lm2) lm2p1 = lm2 + 1 dm2 = vmnorm (n, yh(1,lm2p1), ewt)/cm2(mxords) rh2 = 1.0d0/(1.2d0*dm2**exm2 + 0.0000012d0) go to 476 474 dm2 = dsm*(cm1(nq)/cm2(nq)) rh2 = 1.0d0/(1.2d0*dm2**exsm + 0.0000012d0) nqm2 = nq 476 continue if (rh2 .lt. ratio*rh1) go to 488 c the switch test passed. reset relevant quantities for bdf. ---------- 478 rh = rh2 icount = 20 meth = 2 miter = jtyp pdlast = 0.0d0 nq = nqm2 l = nq + 1 go to 170 c----------------------------------------------------------------------- c we are currently using a bdf method. consider switching to adams. c compute the step size we could have (ideally) used on this step, c with the current (bdf) method, and also that for the adams. c if nq .gt. mxordn, we consider changing to order mxordn on switching. c compare the two step sizes to decide whether to switch. c the step size advantage must be at least 5/ratio = 1 to switch. c if the step size for adams would be so small as to cause c roundoff pollution, we stay with bdf. c----------------------------------------------------------------------- 480 continue exsm = 1.0d0/dfloat(l) if (mxordn .ge. nq) go to 484 nqm1 = mxordn lm1 = mxordn + 1 exm1 = 1.0d0/dfloat(lm1) lm1p1 = lm1 + 1 dm1 = vmnorm (n, yh(1,lm1p1), ewt)/cm1(mxordn) rh1 = 1.0d0/(1.2d0*dm1**exm1 + 0.0000012d0) go to 486 484 dm1 = dsm*(cm2(nq)/cm1(nq)) rh1 = 1.0d0/(1.2d0*dm1**exsm + 0.0000012d0) nqm1 = nq exm1 = exsm 486 rh1it = 2.0d0*rh1 pdh = pdnorm*dabs(h) if (pdh*rh1 .gt. 0.00001d0) rh1it = sm1(nqm1)/pdh rh1 = dmin1(rh1,rh1it) rh2 = 1.0d0/(1.2d0*dsm**exsm + 0.0000012d0) if (rh1*ratio .lt. 5.0d0*rh2) go to 488 alpha = dmax1(0.001d0,rh1) dm1 = (alpha**exm1)*dm1 if (dm1 .le. 1000.0d0*uround*pnorm) go to 488 c the switch test passed. reset relevant quantities for adams. -------- rh = rh1 icount = 20 meth = 1 miter = 0 pdlast = 0.0d0 nq = nqm1 l = nq + 1 go to 170 c c no method switch is being made. do the usual step/order selection. -- 488 continue ialth = ialth - 1 if (ialth .eq. 0) go to 520 if (ialth .gt. 1) go to 700 if (l .eq. lmax) go to 700 do 490 i = 1,n 490 yh(i,lmax) = acor(i) go to 700 c----------------------------------------------------------------------- c the error test failed. kflag keeps track of multiple failures. c restore tn and the yh array to their previous values, and prepare c to try the step again. compute the optimum step size for this or c one lower order. after 2 or more failures, h is forced to decrease c by a factor of 0.2 or less. c----------------------------------------------------------------------- 500 kflag = kflag - 1 tn = told i1 = nqnyh + 1 do 515 jb = 1,nq i1 = i1 - nyh cdir$ ivdep do 510 i = i1,nqnyh 510 yh1(i) = yh1(i) - yh1(i+nyh) 515 continue rmax = 2.0d0 if (dabs(h) .le. hmin*1.00001d0) go to 660 if (kflag .le. -3) go to 640 iredo = 2 rhup = 0.0d0 go to 540 c----------------------------------------------------------------------- c regardless of the success or failure of the step, factors c rhdn, rhsm, and rhup are computed, by which h could be multiplied c at order nq - 1, order nq, or order nq + 1, respectively. c in the case of failure, rhup = 0.0 to avoid an order increase. c the largest of these is determined and the new order chosen c accordingly. if the order is to be increased, we compute one c additional scaled derivative. c----------------------------------------------------------------------- 520 rhup = 0.0d0 if (l .eq. lmax) go to 540 do 530 i = 1,n 530 savf(i) = acor(i) - yh(i,lmax) dup = vmnorm (n, savf, ewt)/tesco(3,nq) exup = 1.0d0/dfloat(l+1) rhup = 1.0d0/(1.4d0*dup**exup + 0.0000014d0) 540 exsm = 1.0d0/dfloat(l) rhsm = 1.0d0/(1.2d0*dsm**exsm + 0.0000012d0) rhdn = 0.0d0 if (nq .eq. 1) go to 550 ddn = vmnorm (n, yh(1,l), ewt)/tesco(1,nq) exdn = 1.0d0/dfloat(nq) rhdn = 1.0d0/(1.3d0*ddn**exdn + 0.0000013d0) c if meth = 1, limit rh according to the stability region also. -------- 550 if (meth .eq. 2) go to 560 pdh = dmax1(dabs(h)*pdlast,0.000001d0) if (l .lt. lmax) rhup = dmin1(rhup,sm1(l)/pdh) rhsm = dmin1(rhsm,sm1(nq)/pdh) if (nq .gt. 1) rhdn = dmin1(rhdn,sm1(nq-1)/pdh) pdest = 0.0d0 560 if (rhsm .ge. rhup) go to 570 if (rhup .gt. rhdn) go to 590 go to 580 570 if (rhsm .lt. rhdn) go to 580 newq = nq rh = rhsm go to 620 580 newq = nq - 1 rh = rhdn if (kflag .lt. 0 .and. rh .gt. 1.0d0) rh = 1.0d0 go to 620 590 newq = l rh = rhup if (rh .lt. 1.1d0) go to 610 r = el(l)/dfloat(l) do 600 i = 1,n 600 yh(i,newq+1) = acor(i)*r go to 630 610 ialth = 3 go to 700 c if meth = 1 and h is restricted by stability, bypass 10 percent test. 620 if (meth .eq. 2) go to 622 if (rh*pdh*1.00001d0 .ge. sm1(newq)) go to 625 622 if (kflag .eq. 0 .and. rh .lt. 1.1d0) go to 610 625 if (kflag .le. -2) rh = dmin1(rh,0.2d0) c----------------------------------------------------------------------- c if there is a change of order, reset nq, l, and the coefficients. c in any case h is reset according to rh and the yh array is rescaled. c then exit from 690 if the step was ok, or redo the step otherwise. c----------------------------------------------------------------------- if (newq .eq. nq) go to 170 630 nq = newq l = nq + 1 iret = 2 go to 150 c----------------------------------------------------------------------- c control reaches this section if 3 or more failures have occured. c if 10 failures have occurred, exit with kflag = -1. c it is assumed that the derivatives that have accumulated in the c yh array have errors of the wrong order. hence the first c derivative is recomputed, and the order is set to 1. then c h is reduced by a factor of 10, and the step is retried, c until it succeeds or h reaches hmin. c----------------------------------------------------------------------- 640 if (kflag .eq. -10) go to 660 rh = 0.1d0 rh = dmax1(hmin/dabs(h),rh) h = h*rh do 645 i = 1,n 645 y(i) = yh(i,1) call f (neq, tn, y, savf) nfe = nfe + 1 do 650 i = 1,n 650 yh(i,2) = h*savf(i) ipup = miter ialth = 5 if (nq .eq. 1) go to 200 nq = 1 l = 2 iret = 3 go to 150 c----------------------------------------------------------------------- c all returns are made through this section. h is saved in hold c to allow the caller to change h on the next step. c----------------------------------------------------------------------- 660 kflag = -1 go to 720 670 kflag = -2 go to 720 680 kflag = -3 go to 720 690 rmax = 10.0d0 700 r = 1.0d0/tesco(2,nqu) do 710 i = 1,n 710 acor(i) = acor(i)*r 720 hold = h jstart = 1 return c----------------------- end of subroutine stoda ----------------------- end