ScaLAPACK 2.1  2.1
ScaLAPACK: Scalable Linear Algebra PACKage
pspocon.f
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1  SUBROUTINE pspocon( UPLO, N, A, IA, JA, DESCA, ANORM, RCOND, WORK,
2  $ LWORK, IWORK, LIWORK, INFO )
3 *
4 * -- ScaLAPACK routine (version 1.7) --
5 * University of Tennessee, Knoxville, Oak Ridge National Laboratory,
6 * and University of California, Berkeley.
7 * May 25, 2001
8 *
9 * .. Scalar Arguments ..
10  CHARACTER UPLO
11  INTEGER IA, INFO, JA, LIWORK, LWORK, N
12  REAL ANORM, RCOND
13 * ..
14 * .. Array Arguments ..
15  INTEGER DESCA( * ), IWORK( * )
16  REAL A( * ), WORK( * )
17 * ..
18 *
19 * Purpose
20 * =======
21 *
22 * PSPOCON estimates the reciprocal of the condition number (in the
23 * 1-norm) of a real symmetric positive definite distributed matrix
24 * using the Cholesky factorization A = U**T*U or A = L*L**T computed by
25 * PSPOTRF.
26 *
27 * An estimate is obtained for norm(inv(A(IA:IA+N-1,JA:JA+N-1))), and
28 * the reciprocal of the condition number is computed as
29 * RCOND = 1 / ( norm( A(IA:IA+N-1,JA:JA+N-1) ) *
30 * norm( inv(A(IA:IA+N-1,JA:JA+N-1)) ) ).
31 *
32 * Notes
33 * =====
34 *
35 * Each global data object is described by an associated description
36 * vector. This vector stores the information required to establish
37 * the mapping between an object element and its corresponding process
38 * and memory location.
39 *
40 * Let A be a generic term for any 2D block cyclicly distributed array.
41 * Such a global array has an associated description vector DESCA.
42 * In the following comments, the character _ should be read as
43 * "of the global array".
44 *
45 * NOTATION STORED IN EXPLANATION
46 * --------------- -------------- --------------------------------------
47 * DTYPE_A(global) DESCA( DTYPE_ )The descriptor type. In this case,
48 * DTYPE_A = 1.
49 * CTXT_A (global) DESCA( CTXT_ ) The BLACS context handle, indicating
50 * the BLACS process grid A is distribu-
51 * ted over. The context itself is glo-
52 * bal, but the handle (the integer
53 * value) may vary.
54 * M_A (global) DESCA( M_ ) The number of rows in the global
55 * array A.
56 * N_A (global) DESCA( N_ ) The number of columns in the global
57 * array A.
58 * MB_A (global) DESCA( MB_ ) The blocking factor used to distribute
59 * the rows of the array.
60 * NB_A (global) DESCA( NB_ ) The blocking factor used to distribute
61 * the columns of the array.
62 * RSRC_A (global) DESCA( RSRC_ ) The process row over which the first
63 * row of the array A is distributed.
64 * CSRC_A (global) DESCA( CSRC_ ) The process column over which the
65 * first column of the array A is
66 * distributed.
67 * LLD_A (local) DESCA( LLD_ ) The leading dimension of the local
68 * array. LLD_A >= MAX(1,LOCr(M_A)).
69 *
70 * Let K be the number of rows or columns of a distributed matrix,
71 * and assume that its process grid has dimension p x q.
72 * LOCr( K ) denotes the number of elements of K that a process
73 * would receive if K were distributed over the p processes of its
74 * process column.
75 * Similarly, LOCc( K ) denotes the number of elements of K that a
76 * process would receive if K were distributed over the q processes of
77 * its process row.
78 * The values of LOCr() and LOCc() may be determined via a call to the
79 * ScaLAPACK tool function, NUMROC:
80 * LOCr( M ) = NUMROC( M, MB_A, MYROW, RSRC_A, NPROW ),
81 * LOCc( N ) = NUMROC( N, NB_A, MYCOL, CSRC_A, NPCOL ).
82 * An upper bound for these quantities may be computed by:
83 * LOCr( M ) <= ceil( ceil(M/MB_A)/NPROW )*MB_A
84 * LOCc( N ) <= ceil( ceil(N/NB_A)/NPCOL )*NB_A
85 *
86 * Arguments
87 * =========
88 *
89 * UPLO (global input) CHARACTER
90 * Specifies whether the factor stored in
91 * A(IA:IA+N-1,JA:JA+N-1) is upper or lower triangular.
92 * = 'U': Upper triangular
93 * = 'L': Lower triangular
94 *
95 * N (global input) INTEGER
96 * The order of the distributed matrix A(IA:IA+N-1,JA:JA+N-1).
97 * N >= 0.
98 *
99 * A (local input) REAL pointer into the local memory to
100 * an array of dimension ( LLD_A, LOCc(JA+N-1) ). On entry, this
101 * array contains the local pieces of the factors L or U from
102 * the Cholesky factorization A(IA:IA+N-1,JA:JA+N-1) = U'*U or
103 * L*L', as computed by PSPOTRF.
104 *
105 * IA (global input) INTEGER
106 * The row index in the global array A indicating the first
107 * row of sub( A ).
108 *
109 * JA (global input) INTEGER
110 * The column index in the global array A indicating the
111 * first column of sub( A ).
112 *
113 * DESCA (global and local input) INTEGER array of dimension DLEN_.
114 * The array descriptor for the distributed matrix A.
115 *
116 * ANORM (global input) REAL
117 * The 1-norm (or infinity-norm) of the symmetric distributed
118 * matrix A(IA:IA+N-1,JA:JA+N-1).
119 *
120 * RCOND (global output) REAL
121 * The reciprocal of the condition number of the distributed
122 * matrix A(IA:IA+N-1,JA:JA+N-1), computed as
123 * RCOND = 1 / ( norm( A(IA:IA+N-1,JA:JA+N-1) ) *
124 * norm( inv(A(IA:IA+N-1,JA:JA+N-1)) ) ).
125 *
126 * WORK (local workspace/local output) REAL array,
127 * dimension (LWORK)
128 * On exit, WORK(1) returns the minimal and optimal LWORK.
129 *
130 * LWORK (local or global input) INTEGER
131 * The dimension of the array WORK.
132 * LWORK is local input and must be at least
133 * LWORK >= 2*LOCr(N+MOD(IA-1,MB_A)) + 2*LOCc(N+MOD(JA-1,NB_A))+
134 * MAX( 2, MAX(NB_A*CEIL(NPROW-1,NPCOL),LOCc(N+MOD(JA-1,NB_A)) +
135 * NB_A*CEIL(NPCOL-1,NPROW)) ).
136 *
137 * If LWORK = -1, then LWORK is global input and a workspace
138 * query is assumed; the routine only calculates the minimum
139 * and optimal size for all work arrays. Each of these
140 * values is returned in the first entry of the corresponding
141 * work array, and no error message is issued by PXERBLA.
142 *
143 * IWORK (local workspace/local output) INTEGER array,
144 * dimension (LIWORK)
145 * On exit, IWORK(1) returns the minimal and optimal LIWORK.
146 *
147 * LIWORK (local or global input) INTEGER
148 * The dimension of the array IWORK.
149 * LIWORK is local input and must be at least
150 * LIWORK >= LOCr(N+MOD(IA-1,MB_A)).
151 *
152 * If LIWORK = -1, then LIWORK is global input and a workspace
153 * query is assumed; the routine only calculates the minimum
154 * and optimal size for all work arrays. Each of these
155 * values is returned in the first entry of the corresponding
156 * work array, and no error message is issued by PXERBLA.
157 *
158 *
159 * INFO (global output) INTEGER
160 * = 0: successful exit
161 * < 0: If the i-th argument is an array and the j-entry had
162 * an illegal value, then INFO = -(i*100+j), if the i-th
163 * argument is a scalar and had an illegal value, then
164 * INFO = -i.
165 *
166 * =====================================================================
167 *
168 * .. Parameters ..
169  INTEGER BLOCK_CYCLIC_2D, CSRC_, CTXT_, DLEN_, DTYPE_,
170  $ lld_, mb_, m_, nb_, n_, rsrc_
171  parameter( block_cyclic_2d = 1, dlen_ = 9, dtype_ = 1,
172  $ ctxt_ = 2, m_ = 3, n_ = 4, mb_ = 5, nb_ = 6,
173  $ rsrc_ = 7, csrc_ = 8, lld_ = 9 )
174  REAL ONE, ZERO
175  parameter( one = 1.0e+0, zero = 0.0e+0 )
176 * ..
177 * .. Local Scalars ..
178  LOGICAL LQUERY, UPPER
179  CHARACTER CBTOP, COLCTOP, NORMIN, ROWCTOP
180  INTEGER IACOL, IAROW, ICOFF, ICTXT, IIA, IPNL, IPNU,
181  $ ipv, ipw, ipx, iroff, iv, ix, ixx, jja, jv,
182  $ jx, kase, liwmin, lwmin, mycol, myrow, np,
183  $ npcol, nprow, npmod, nq, nqmod
184  REAL AINVNM, SCALE, SL, SU, SMLNUM
185  REAL WMAX
186 * ..
187 * .. Local Arrays ..
188  INTEGER DESCV( DLEN_ ), DESCX( DLEN_ ), IDUM1( 3 ),
189  $ idum2( 3 )
190 * ..
191 * .. External Subroutines ..
192  EXTERNAL blacs_gridinfo, chk1mat, descset, infog2l,
193  $ pchk1mat, psamax, pslatrs, pslacon,
194  $ psrscl, pb_topget, pb_topset, pxerbla, sgebr2d,
195  $ sgebs2d
196 * ..
197 * .. External Functions ..
198  LOGICAL LSAME
199  INTEGER ICEIL, INDXG2P, NUMROC
200  REAL PSLAMCH
201  EXTERNAL iceil, indxg2p, lsame, numroc, pslamch
202 * ..
203 * .. Intrinsic Functions ..
204  INTRINSIC abs, ichar, max, mod, real
205 * ..
206 * .. Executable Statements ..
207 *
208 * Get grid parameters
209 *
210  ictxt = desca( ctxt_ )
211  CALL blacs_gridinfo( ictxt, nprow, npcol, myrow, mycol )
212 *
213 * Test the input parameters
214 *
215  info = 0
216  IF( nprow.EQ.-1 ) THEN
217  info = -(600+ctxt_)
218  ELSE
219  CALL chk1mat( n, 2, n, 2, ia, ja, desca, 6, info )
220  IF( info.EQ.0 ) THEN
221  upper = lsame( uplo, 'U' )
222  iarow = indxg2p( ia, desca( mb_ ), myrow, desca( rsrc_ ),
223  $ nprow )
224  iacol = indxg2p( ja, desca( nb_ ), mycol, desca( csrc_ ),
225  $ npcol )
226  npmod = numroc( n + mod( ia-1, desca( mb_ ) ), desca( mb_ ),
227  $ myrow, iarow, nprow )
228  nqmod = numroc( n + mod( ja-1, desca( nb_ ) ), desca( nb_ ),
229  $ mycol, iacol, npcol )
230  lwmin = 2*npmod + 2*nqmod +
231  $ max( 2, max( desca( nb_ )*
232  $ max( 1, iceil( nprow-1, npcol ) ), nqmod +
233  $ desca( nb_ )*
234  $ max( 1, iceil( npcol-1, nprow ) ) ) )
235  work( 1 ) = real( lwmin )
236  liwmin = npmod
237  iwork( 1 ) = liwmin
238  lquery = ( lwork.EQ.-1 .OR. liwork.EQ.-1 )
239 *
240  IF( .NOT.upper .AND. .NOT.lsame( uplo, 'L' ) ) THEN
241  info = -1
242  ELSE IF( anorm.LT.zero ) THEN
243  info = -7
244  ELSE IF( lwork.LT.lwmin .AND. .NOT.lquery ) THEN
245  info = -10
246  ELSE IF( liwork.LT.liwmin .AND. .NOT.lquery ) THEN
247  iwork( 1 ) = liwmin
248  info = -12
249  END IF
250  END IF
251 *
252  IF( upper ) THEN
253  idum1( 1 ) = ichar( 'U' )
254  ELSE
255  idum1( 1 ) = ichar( 'L' )
256  END IF
257  idum2( 1 ) = 1
258  IF( lwork.EQ.-1 ) THEN
259  idum1( 2 ) = -1
260  ELSE
261  idum1( 2 ) = 1
262  END IF
263  idum2( 2 ) = 10
264  IF( liwork.EQ.-1 ) THEN
265  idum1( 3 ) = -1
266  ELSE
267  idum1( 3 ) = 1
268  END IF
269  idum2( 3 ) = 12
270  CALL pchk1mat( n, 2, n, 2, ia, ja, desca, 6, 3, idum1, idum2,
271  $ info )
272  END IF
273 *
274  IF( info.NE.0 ) THEN
275  CALL pxerbla( ictxt, 'PSPOCON', -info )
276  RETURN
277  ELSE IF( lquery ) THEN
278  RETURN
279  END IF
280 *
281 * Quick return if possible
282 *
283  rcond = zero
284  IF( n.EQ.0 ) THEN
285  rcond = one
286  RETURN
287  ELSE IF( anorm.EQ.zero ) THEN
288  RETURN
289  ELSE IF( n.EQ.1 ) THEN
290  rcond = one
291  RETURN
292  END IF
293 *
294  CALL pb_topget( ictxt, 'Combine', 'Columnwise', colctop )
295  CALL pb_topget( ictxt, 'Combine', 'Rowwise', rowctop )
296  CALL pb_topset( ictxt, 'Combine', 'Columnwise', '1-tree' )
297  CALL pb_topset( ictxt, 'Combine', 'Rowwise', '1-tree' )
298 *
299  smlnum = pslamch( ictxt, 'Safe minimum' )
300  iroff = mod( ia-1, desca( mb_ ) )
301  icoff = mod( ja-1, desca( nb_ ) )
302  CALL infog2l( ia, ja, desca, nprow, npcol, myrow, mycol, iia, jja,
303  $ iarow, iacol )
304  np = numroc( n+iroff, desca( mb_ ), myrow, iarow, nprow )
305  nq = numroc( n+icoff, desca( nb_ ), mycol, iacol, npcol )
306  iv = iroff + 1
307  ix = iv
308  jv = icoff + 1
309  jx = jv
310 *
311  ipx = 1
312  ipv = ipx + np
313  ipnl = ipv + np
314  ipnu = ipnl + nq
315  ipw = ipnu + nq
316 *
317  CALL descset( descv, n+iroff, 1, desca( mb_ ), 1, iarow, mycol,
318  $ ictxt, max( 1, np ) )
319  CALL descset( descx, n+iroff, 1, desca( mb_ ), 1, iarow, mycol,
320  $ ictxt, max( 1, np ) )
321 *
322 * Estimate the 1-norm (or I-norm) of inv(A).
323 *
324  ainvnm = zero
325  kase = 0
326  normin = 'N'
327 *
328  10 CONTINUE
329  CALL pslacon( n, work( ipv ), iv, jv, descv, work( ipx ), ix, jx,
330  $ descx, iwork, ainvnm, kase )
331  IF( kase.NE.0 ) THEN
332  IF( upper ) THEN
333 *
334 * Multiply by inv(U').
335 *
336  descx( csrc_ ) = iacol
337  CALL pslatrs( 'Upper', 'Transpose', 'Non-unit', normin,
338  $ n, a, ia, ja, desca, work( ipx ), ix, jx,
339  $ descx, sl, work( ipnl ), work( ipw ) )
340  descx( csrc_ ) = mycol
341  normin = 'Y'
342 *
343 * Multiply by inv(U).
344 *
345  descx( csrc_ ) = iacol
346  CALL pslatrs( 'Upper', 'No transpose', 'Non-unit', normin,
347  $ n, a, ia, ja, desca, work( ipx ), ix, jx,
348  $ descx, su, work( ipnu ), work( ipw ) )
349  descx( csrc_ ) = mycol
350  ELSE
351 *
352 * Multiply by inv(L).
353 *
354  descx( csrc_ ) = iacol
355  CALL pslatrs( 'Lower', 'No transpose', 'Non-unit', normin,
356  $ n, a, ia, ja, desca, work( ipx ), ix, jx,
357  $ descx, sl, work( ipnl ), work( ipw ) )
358  descx( csrc_ ) = mycol
359  normin = 'Y'
360 *
361 * Multiply by inv(L').
362 *
363  descx( csrc_ ) = iacol
364  CALL pslatrs( 'Lower', 'Transpose', 'Non-unit', normin,
365  $ n, a, ia, ja, desca, work( ipx ), ix, jx,
366  $ descx, su, work( ipnu ), work( ipw ) )
367  descx( csrc_ ) = mycol
368  END IF
369 *
370 * Multiply by 1/SCALE if doing so will not cause overflow.
371 *
372  scale = sl*su
373  IF( scale.NE.one ) THEN
374  CALL psamax( n, wmax, ixx, work( ipx ), ix, jx, descx, 1 )
375  IF( descx( m_ ).EQ.1 .AND. n.EQ.1 ) THEN
376  CALL pb_topget( ictxt, 'Broadcast', 'Columnwise', cbtop )
377  IF( myrow.EQ.iarow ) THEN
378  CALL sgebs2d( ictxt, 'Column', cbtop, 1, 1, wmax, 1 )
379  ELSE
380  CALL sgebr2d( ictxt, 'Column', cbtop, 1, 1, wmax, 1,
381  $ iarow, mycol )
382  END IF
383  END IF
384  IF( scale.LT.abs( wmax )*smlnum .OR. scale.EQ.zero )
385  $ GO TO 20
386  CALL psrscl( n, scale, work( ipx ), ix, jx, descx, 1 )
387  END IF
388  GO TO 10
389  END IF
390 *
391 * Compute the estimate of the reciprocal condition number.
392 *
393  IF( ainvnm.NE.zero )
394  $ rcond = ( one / ainvnm ) / anorm
395 *
396  20 CONTINUE
397 *
398  CALL pb_topset( ictxt, 'Combine', 'Columnwise', colctop )
399  CALL pb_topset( ictxt, 'Combine', 'Rowwise', rowctop )
400 *
401  RETURN
402 *
403 * End of PSPOCON
404 *
405  END
pslatrs
subroutine pslatrs(UPLO, TRANS, DIAG, NORMIN, N, A, IA, JA, DESCA, X, IX, JX, DESCX, SCALE, CNORM, WORK)
Definition: pslatrs.f:4
max
#define max(A, B)
Definition: pcgemr.c:180
infog2l
subroutine infog2l(GRINDX, GCINDX, DESC, NPROW, NPCOL, MYROW, MYCOL, LRINDX, LCINDX, RSRC, CSRC)
Definition: infog2l.f:3
pspocon
subroutine pspocon(UPLO, N, A, IA, JA, DESCA, ANORM, RCOND, WORK, LWORK, IWORK, LIWORK, INFO)
Definition: pspocon.f:3
psrscl
subroutine psrscl(N, SA, SX, IX, JX, DESCX, INCX)
Definition: psrscl.f:2
pslacon
subroutine pslacon(N, V, IV, JV, DESCV, X, IX, JX, DESCX, ISGN, EST, KASE)
Definition: pslacon.f:3
pchk1mat
subroutine pchk1mat(MA, MAPOS0, NA, NAPOS0, IA, JA, DESCA, DESCAPOS0, NEXTRA, EX, EXPOS, INFO)
Definition: pchkxmat.f:3
descset
subroutine descset(DESC, M, N, MB, NB, IRSRC, ICSRC, ICTXT, LLD)
Definition: descset.f:3
chk1mat
subroutine chk1mat(MA, MAPOS0, NA, NAPOS0, IA, JA, DESCA, DESCAPOS0, INFO)
Definition: chk1mat.f:3
pxerbla
subroutine pxerbla(ICTXT, SRNAME, INFO)
Definition: pxerbla.f:2