File: pbcherk.f

package info (click to toggle)
scalapack 1.6-13
  • links: PTS
  • area: main
  • in suites: potato
  • size: 30,476 kB
  • ctags: 25,789
  • sloc: fortran: 296,718; ansic: 51,265; makefile: 1,541; sh: 4
file content (852 lines) | stat: -rw-r--r-- 33,107 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
      SUBROUTINE PBCHERK( ICONTXT, MATBLK, UPLO, TRANS, N, K, NB, ALPHA,
     $                    A, LDA, BETA, C, LDC, IAPOS, ICROW, ICCOL,
     $                    ACOMM, AWORK, CWORK, MULLEN, WORK )
*
*  -- PB-BLAS routine (version 2.1) --
*     University of Tennessee, Knoxville, Oak Ridge National Laboratory.
*     April 28, 1996
*
*     Jaeyoung Choi, Oak Ridge National Laboratory
*     Jack Dongarra, University of Tennessee and Oak Ridge National Lab.
*     David Walker,  Oak Ridge National Laboratory
*
*     .. Scalar Arguments ..
      CHARACTER*1        ACOMM, AWORK, CWORK, MATBLK, TRANS, UPLO
      INTEGER            IAPOS, ICCOL, ICONTXT, ICROW, K, LDA, LDC,
     $                   MULLEN, N, NB
      REAL                ALPHA, BETA
*     ..
*     .. Array Arguments ..
      COMPLEX             A( LDA, * ), C( LDC, * ), WORK( * )
*     ..
*
*  Purpose
*  =======
*
*  PBCHERK is a parallel blocked version of CHERK.
*  PBCHERK  performs one of the Hermitian rank k operations
*
*     C := alpha*A*A' + beta*C,
*
*  or
*
*     C := alpha*A'*A + beta*C,
*
*  where  alpha and beta  are scalars,  C is an N-by-N Hermitian matrix
*  and  A  is an  N-by-K matrix in the first case and  a K-by-N matrix
*  in the second case.
*
*  The first elements  of the matrices A, and C  should  be  located  at
*  the beginnings of their first blocks. (not the middle of the blocks.)
*  A can be broadcast if necessary  and then transposed.  The communica-
*  tion scheme can be selected.
*
*  Parameters
*  ==========
*
*  ICONTXT (input) INTEGER
*          ICONTXT is the BLACS mechanism for partitioning communication
*          space.  A defining property of a context is that a message in
*          a context cannot be sent or received in another context.  The
*          BLACS context includes the definition of a grid, and each
*          process' coordinates in it.
*
*  MATBLK  (input) CHARACTER*1
*          MATBLK specifies whether C is a (full) block matrix or
*          a single block as follows:
*
*             MATBLK = 'M',  C is a (full) block matrix,
*             MATBLK = 'B',  C is a single block.
*
*  UPLO    (input) CHARACTER*1
*          UPLO specifies whether the upper or lower triangular part of
*          the array C is to be referenced as follows:
*
*             UPLO = 'U',  Only the  upper triangular part of  C
*                          is to be referenced.
*             UPLO = 'L',  Only the  lower triangular part of  C
*                          is to be referenced.
*
*  TRANS   (input) CHARACTER*1
*          TRANS specifies the operation to be performed as follows:
*
*             TRANS = 'N',   C := alpha*A*A' + beta*C.
*             TRANS = 'C',   C := alpha*A'*A + beta*C.
*
*  N       (input) INTEGER
*          N specifies the order of the matrix C.  N >= 0.
*
*  K       (input) INTEGER
*          If TRANS = 'N',  K specifies  the number of  columns of  the
*          matrix A, and if TRANS = 'C', K specifies the number of rows
*          of the matrix A.  K >= 0.
*
*  NB      (input) INTEGER
*          NB specifies the row and column block size of the matrix C.
*          It also specifies the row block size of the matrix A if
*          MATBLK = 'M' and TRANS = 'N', or MATBLK = 'B' and TRANS='C';
*          and the column block size of the matrix A if MATBLK = 'M' and
*          TRANS = 'C', or MATBLK = 'B' and TRANS = 'N'.  NB >= 1.
*
*  ALPHA   (input) REAL
*          ALPHA specifies the scalar alpha.
*
*  A       (input) COMPLEX array of local DIMENSION ( LDA, ka ),
*          where ka is Kq when TRANS = 'N', or Nq otherwise.
*          If TRANS = 'N', the leading Np-by-Kq part of the array A
*          must contain the (local) matrix A, otherwise the leading Kp-
*          by-Nq part of the array A must contain the (local) matrix A.
*
*  LDA     (input) INTEGER
*          LDA specifies the leading dimension of (local) A as declared
*          in the calling (sub) program.
*          LDA >= MAX(1,Np) if MATBLK = 'M' & TRANS = 'N',
*                           or MATBLK = 'B' & TRANS = 'C',
*          LDA >= MAX(1,Kp) if MATBLK = 'M' & TRANS = 'C',
*                           or MATBLK = 'B' & TRANS = 'N'.
*  BETA    (input) REAL
*          BETA specifies the scalar beta.
*
*  C       (input/output) COMPLEX array of local DIMENSION ( LDC, Nq ).
*          On entry with UPLO = 'U', the leading N-by-N upper triangular
*          part of the (global) array C must contain the upper triangu-
*          lar part  of the  Hermitian matrix  and the strictly lower
*          triangular part  of C is not referenced. On exit, the upper
*          triangular part of the array  C is overwritten by the upper
*          triangular part of the updated  matrix.
*          On entry with  UPLO='L', the leading N-by-N lower triangular
*          part of the (global) array C  must  contain the lower
*          triangular  part  of the  Hermitian  matrix and the strictly
*          upper triangular part of C is not referenced.  On exit,
*          the lower triangular part of the array C is overwritten by
*          the lower triangular part of the updated matrix.
*
*  LDC     (input) INTEGER
*          LDC specifies the leading dimension of (local) C as declared
*          in the calling (sub) program.  LDC >= MAX(1,Np).
*
*  IAPOS   (input) INTEGER
*          If TRANS = 'N', IAPOS specifies a column of process
*          template, which holds the first block of A.  And if TRANS =
*          'C', IAPOS specifies a row of the template, which holds the
*          first block of A.  If MATBLK = 'M' and all columns or rows
*          of processes have a copy of A, then set IAPOS = -1.
*
*  ICROW   (input) INTEGER
*          It specifies a row of process template which has the
*          first block of C.  It also represents the first (row)
*          process of the column block C if TRANS = 'N'.
*          When MATBLK = 'B', and all rows of processes have their
*          own copies of C, set ICROW =  -1.
*
*  ICCOL   (input) INTEGER
*          It specifies a column of process template which has the
*          first block of C.  It also represents the  first (column)
*          process  of the row block C if TRANS = 'C'.
*          When MATBLK = 'B', and all columns of processes have
*          their own copies of C, set ICCOL = -1.
*
*  ACOMM   (input) CHARACTER*1
*          When MATBLK = 'M', ACOMM specifies the communication scheme
*          of column or row block of A if communication is necessary.
*          It follows topology definition of BLACS.
*          When MATBLK = 'B', the argument is ignored.
*
*  AWORK   (input) CHARACTER*1
*          When MATBLK = 'M', AWORK determines whether A is a
*          workspace or not.
*
*             AWORK = 'Y':  A is workspace in other processes.
*                           A is sent to A position in other processes.
*                           It is assumed that processes have
*                           sufficient space to store (local) A.
*             AWORK = 'N':  Data in A will be untouched (unchanged).
*
*          When MATBLK = 'B', it is ignored.
*
*  CWORK   (input) CHARACTER*1
*          When MATBLK = 'M', CWORK determines whether the other
*          triangular part of C is accessed and modified or not.
*
*            CWORK = 'N': if UPLO = 'U', only upper triangular portion
*                         portion of the matrix C is accessed and the
*                         lower triangular portion is untouched.
*                         Likewise if UPLO = 'L', only lower triangular
*                         portion of the matrix C is accessed and the
*                         upper triangular portion is untouched.
*            CWORK = 'Y': if UPLO = 'U', only lower triangular portion
*                         of the matrix C may be accessed and modified
*                         for fast computation.  And if UPLO = 'L', the
*                         upper triangular portion of the matrix C may
*                         be accessed and modified for fast computation.
*
*          And when MATBLK = 'B', CWORK determines whether C is a
*          workspace or not.
*
*             CWORK = 'Y':  C is workspace in other processes.
*                           C is sent to C position in other processes.
*                           It is assumed that processes have
*                           sufficient space to store C.
*             CWORK = 'N':  Data in C will be untouched (unchanged)
*                           in other processes.
*
*  MULLEN  (input) INTEGER
*          When MATBLK = 'M', MULLEN specifies multiplication length of
*          the optimum column number of a row block A if TRANS = 'C',
*          or A' if TRANS = 'N' for multiplying A with A'.  The value
*          depends on machine characteristics.
*          When MATBLK = 'B', it is ignored.
*
*  WORK    (workspace) COMPLEX array of dimension Size(WORK).
*          It will store copy of A and/or A'.
*
*  Parameters Details
*  ==================
*
*  Lx      It is  a local portion  of L  owned  by  a process,  (L is
*          replaced by M, or N,  and x  is replaced  by  either  p
*          (=NPROW) or q (=NPCOL)).  The value is determined by  L, LB,
*          x, and MI,  where  LB is  a block size  and MI is a  row  or
*          column position in a process template.  Lx is equal to  or
*          less than  Lx0 = CEIL( L, LB*x ) * LB.
*
*  Memory Requirement of WORK
*  ==========================
*
*  Npb    = CEIL( N, NB*NPROW )
*  Nqb    = CEIL( N, NB*NPCOL )
*  Np0    = NUMROC( N, NB, 0, 0, NPROW ) ~= Npb * NB
*  Nq0    = NUMROC( N, NB, 0, 0, NPCOL ) ~= Nqb * NB
*  LCMQ   = LCM / NPCOL
*  LCMP   = LCM / NPROW
*  ISZCMP = CEIL(MULLEN, LCMQ*NB)
*  SZCMP  = ISZCMP * ISZCMP * LCMQ*NB * LCMP*NB
*
*  (1) MATBLK = 'M'
*    (a) TRANS = 'N'
*    Size(WORK) = K * Nq0
*               + K * Np0        ( if IAPOS <> -1 and AWORK <> 'Y' )
*               + MAX[ SZCMP                     ( if CWORK <> 'Y' ),
*                      K*CEIL(Nqb,LCMQ)*NB*MIN(LCMQ,CEIL(N,NB) ]
*    (b) TRANS = 'C'
*    Size(WORK) = K * Np0
*               + K * Nq0        ( if IAPOS <> -1 and AWORK <> 'Y' )
*               + MAX[ SZCMP                     ( if CWORK <> 'Y' ),
*                      K*CEIL(Npb,LCMP)*NB*MIN(LCMP,CEIL(N,NB) ]
*
*  (2) MATBLK = 'B'
*    (a) TRANS = 'N'     (on a row of processes ICROW only )
*    Size(WORK) = N * (N+1) / 2     ( if CWORK =  'Y')
*    Size(WORK) = N * N             ( if CWORK <> 'Y')
*    (b) TRANS = 'C' (on a column of processes ICCOL only )
*    Size(WORK) = N * (N+1) / 2     ( if CWORK =  'Y')
*    Size(WORK) = N * N             ( if CWORK <> 'Y')
*
*  Notes
*  -----
*  More precise space can be computed as
*
*  CEIL(Nqb,LCMQ)*NB => NUMROC( NUMROC(N,NB,0,0,NPCOL), NB, 0, 0, LCMQ )
*                    = NUMROC( Nq0, NB, 0, 0, LCMQ )
*  CEIL(Npb,LCMP)*NB => NUMROC( NUMROC(N,NB,0,0,NPROW), NB, 0, 0, LCMP )
*                    = NUMROC( Np0, NB, 0, 0, LCMP )
*
*  =====================================================================
*
*     .. Parameters ..
      REAL               RONE, RZERO
      PARAMETER          ( RONE = 1.0E+0, RZERO = 0.0E+0 )
      COMPLEX            ONE,  ZERO
      PARAMETER          ( ONE  = ( 1.0E+0, 0.0E+0 ),
     $                   ZERO = ( 0.0E+0, 0.0E+0 ) )
*     ..
*     .. Local Scalars ..
      CHARACTER*1        COMMA, FORM
      LOGICAL            ADATA, ASPACE, CMAT, CSPACE, NOTRAN, UPPER
      INTEGER            INFO, IPBZ, IPT, IPW, IQBZ, ISZCMP, JJ, JNPBZ,
     $                   JPBZ, JQBZ, KI, KIZ, KJ, KJZ, LCM, LCMP, LCMQ,
     $                   LKK, LMW, LNW, LPBZ, LQBZ, MRCOL, MRROW, MYCOL,
     $                   MYROW, MZCOL, MZROW, NP, NPCOL, NPROW, NQ
      COMPLEX            TALPHA, TBETA
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      INTEGER            ICEIL, ILCM, NUMROC
      EXTERNAL           ICEIL, ILCM, LSAME, NUMROC
*     ..
*     .. External Subroutines ..
      EXTERNAL           BLACS_GRIDINFO, CGEBR2D, CGEBS2D, CGEMM, CHERK,
     $                   PBCMATADD, PBCT1CPY, PBCT2CPY, PBCT3CPY,
     $                   PBCTRADD, PBCTRAN, PXERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          CMPLX, MAX, MIN
*     ..
*     .. Executable Statements ..
*
*     Quick return if possible.
*
      IF( N.EQ.0 .OR.
     $    ( ( ALPHA.EQ.RZERO .OR. K.EQ.0 ) .AND. BETA.EQ.RONE ) )
     $   RETURN
*
      CALL BLACS_GRIDINFO( ICONTXT, NPROW, NPCOL, MYROW, MYCOL )
*
      CMAT   = LSAME( MATBLK, 'M' )
      UPPER  = LSAME( UPLO,   'U' )
      NOTRAN = LSAME( TRANS,  'N' )
*
*     Test the input parameters.
*
      INFO = 0
      IF(      ( .NOT.CMAT                 ).AND.
     $         ( .NOT.LSAME( MATBLK, 'B' ) )         ) THEN
         INFO = 2
      ELSE IF( ( .NOT.UPPER                ).AND.
     $         ( .NOT.LSAME( UPLO,   'L' ) )         ) THEN
         INFO = 3
      ELSE IF( ( .NOT.NOTRAN               ).AND.
     $         ( .NOT.LSAME( TRANS,  'C' ) )         ) THEN
         INFO = 4
      ELSE IF( N  .LT.0                              ) THEN
         INFO = 5
      ELSE IF( K  .LT.0                              ) THEN
         INFO = 6
      ELSE IF( NB .LT.1                              ) THEN
         INFO = 7
      END IF
*
   10 CONTINUE
      IF( INFO.NE.0 ) THEN
         CALL PXERBLA( ICONTXT, 'PBCHERK ', INFO )
         RETURN
      END IF
*
*     Start the operations.
*
* === If C is a matrix ===
*
      IF( CMAT ) THEN
        NP = NUMROC( N, NB, MYROW, ICROW, NPROW )
        NQ = NUMROC( N, NB, MYCOL, ICCOL, NPCOL )
*
        IF( LDC.LT.MAX(1,NP)                    ) THEN
          INFO = 13
        ELSE IF( ICROW.LT.0 .OR. ICROW.GE.NPROW ) THEN
          INFO = 15
        ELSE IF( ICCOL.LT.0 .OR. ICCOL.GE.NPCOL ) THEN
          INFO = 16
        END IF
*
        ADATA  = .FALSE.
        IF( IAPOS.EQ.-1 ) ADATA = .TRUE.
        CSPACE = LSAME( CWORK, 'Y' )
        ASPACE = LSAME( AWORK, 'Y' )
        COMMA = ACOMM
        IF( LSAME( COMMA, ' ' ) ) COMMA = '1'
*
*       LCM : the least common multiple of NPROW and NPCOL
*
        LCM  = ILCM( NPROW, NPCOL )
        LCMP = LCM  / NPROW
        LCMQ = LCM  / NPCOL
        LPBZ = LCMP * NB
        LQBZ = LCMQ * NB
*
        MRROW = MOD( NPROW+MYROW-ICROW, NPROW )
        MRCOL = MOD( NPCOL+MYCOL-ICCOL, NPCOL )
        TALPHA = CMPLX( ALPHA )
        TBETA  = CMPLX( BETA )
        LKK = MAX( 1, K )
*
*       PART 1: Distribute a column (or row) block A and its transpose A
*       ================================================================
*
        IF( NOTRAN ) THEN
*
*         Form  C := alpha*A*A' + beta*C.
*       _____________         _                           _____________
*      |\_           |       | |                         |\_           |
*      |  \_         |       | |                         |  \_         |
*      |    \_       |       | |    _____________        |    \_       |
*      |      C_     | = a * |A| * |_____(A')____| + b * |      C_     |
*      |        \_   |       | |                         |        \_   |
*      |          \_ |       | |                         |          \_ |
*      |____________\|       |_|                         |____________\|
*
          IF( LDA.LT.MAX(1,NP) .AND. ( ASPACE .OR.
     $        IAPOS.EQ.MYCOL .OR. IAPOS.EQ.-1 )    ) THEN
            INFO = 10
          ELSE IF( IAPOS.LT.-1 .OR. IAPOS.GE.NPCOL ) THEN
            INFO = 14
          END IF
          IF( INFO.NE.0 ) GO TO 10
*
*         Broadcast A if necessary
*
          IPT = 1
          IF( .NOT.ADATA ) THEN
            IF( ASPACE ) THEN
              IF( MYCOL.EQ.IAPOS ) THEN
                CALL CGEBS2D( ICONTXT, 'Row', COMMA, NP, K, A, LDA )
              ELSE
                CALL CGEBR2D( ICONTXT, 'Row', COMMA, NP, K, A, LDA,
     $                        MYROW, IAPOS )
              END IF
              ADATA = .TRUE.
            ELSE
              IF( MYCOL.EQ.IAPOS ) THEN
                CALL PBCMATADD( ICONTXT, 'V', NP, K, ONE, A, LDA, ZERO,
     $                          WORK, NP )
                CALL CGEBS2D( ICONTXT, 'Row', COMMA, NP, K, WORK, NP )
              ELSE
                CALL CGEBR2D( ICONTXT, 'Row', COMMA, NP, K, WORK, NP,
     $                        MYROW, IAPOS )
              END IF
              IPT = NP * K + 1
            END IF
          END IF
*
*         Transpose col block of A to WORK(IPT), where A is distributed
*
          IPW = K * NQ + IPT
          IF( ADATA ) THEN
            CALL PBCTRAN( ICONTXT, 'Col', 'C', N, K, NB, A, LDA, ZERO,
     $                    WORK(IPT), K, ICROW, -1, -1, ICCOL,
     $                    WORK(IPW) )
          ELSE
            CALL PBCTRAN( ICONTXT, 'Col', 'C', N, K, NB, WORK, NP, ZERO,
     $                    WORK(IPT), K, ICROW, -1, -1, ICCOL,
     $                    WORK(IPW) )
          END IF
*
        ELSE
*
*         Form  C := alpha*A'*A + beta*C.
*       _____________          _                          _____________
*      |\_           |        | |                        |\_           |
*      |  \_         |        | |                        |  \_         |
*      |    \_       |        | |   _____________        |    \_       |
*      |      C_     | = a * ( A')*|______A______| + b * |      C_     |
*      |        \_   |        | |                        |        \_   |
*      |          \_ |        | |                        |          \_ |
*      |____________\|        |_|                        |____________\|
*
          IF( LDA.LT.MAX(1,K) .AND. ( ASPACE .OR.
     $        IAPOS.EQ.MYROW .OR. IAPOS.EQ.-1 )    ) THEN
            INFO = 10
          ELSE IF( IAPOS.LT.-1 .OR. IAPOS.GE.NPROW ) THEN
            INFO = 14
          END IF
          IF( INFO.NE.0 ) GO TO 10
*
*         Broadcast A if necessary
*
          IPT= 1
          IF( .NOT.ADATA ) THEN
            IF( ASPACE ) THEN
              IF( MYROW.EQ.IAPOS ) THEN
                CALL CGEBS2D( ICONTXT, 'Col', COMMA, K, NQ, A, LDA )
              ELSE
                CALL CGEBR2D( ICONTXT, 'Col', COMMA, K, NQ, A, LDA,
     $                        IAPOS, MYCOL )
              END IF
              ADATA = .TRUE.
            ELSE
              IF( MYROW.EQ.IAPOS ) THEN
                CALL PBCMATADD( ICONTXT, 'G', K, NQ, ONE, A, LDA, ZERO,
     $                          WORK, K )
                CALL CGEBS2D( ICONTXT, 'Col', COMMA, K, NQ, WORK, K )
              ELSE
                CALL CGEBR2D( ICONTXT, 'Col', COMMA, K, NQ, WORK, K,
     $                        IAPOS, MYCOL )
              END IF
              IPT = K * NQ + 1
            END IF
          END IF
*
*         Transpose row block of A to WORK(IPT), where A is distributed
*
          IPW = NP * K + IPT
          IF( ADATA ) THEN
            CALL PBCTRAN( ICONTXT, 'Row', 'C', K, N, NB, A, LDA, ZERO,
     $                    WORK(IPT), NP, -1, ICCOL, ICROW, -1,
     $                    WORK(IPW) )
          ELSE
            CALL PBCTRAN( ICONTXT, 'Row', 'C', K, N, NB, WORK,K, ZERO,
     $                    WORK(IPT), NP, -1, ICCOL, ICROW, -1,
     $                    WORK(IPW) )
          END IF
        END IF
*
*       PART 2: Update C with A and A'
*       ==============================
*
        IF( NP.EQ.0 .OR. NQ.EQ.0 ) RETURN
*
*       If C is a Hermitian upper triangular matrix,
*
        IF( UPPER ) THEN
          ISZCMP = ICEIL( MULLEN, LQBZ )
          IF( ISZCMP.LE.0 ) ISZCMP = 1
          IPBZ = ISZCMP * LPBZ
          IQBZ = ISZCMP * LQBZ
          JPBZ = 0
          JQBZ = 0
*
          DO 40 JJ = 1, ICEIL(NQ, IQBZ)
            LMW = MIN( IPBZ, NP-JPBZ )
            LNW = MIN( IQBZ, NQ-JQBZ )
            JNPBZ = JPBZ + LMW
*
*           Modify (change) data in the lower triangular part
*
            IF( CSPACE ) THEN
*
*             Update C := alpha*A*A' + beta*C, if TRANS = 'N'
*
              IF( NOTRAN ) THEN
                IF( ADATA ) THEN
                  CALL CGEMM( 'No', 'No', JNPBZ, LNW, K, TALPHA,
     $                        A, LDA, WORK(JQBZ*K+IPT), LKK, TBETA,
     $                        C(1,JQBZ+1), LDC )
                ELSE
                  CALL CGEMM( 'No', 'No', JNPBZ, LNW, K, TALPHA,
     $                        WORK, NP, WORK(JQBZ*K+IPT), LKK, TBETA,
     $                        C(1,JQBZ+1), LDC )
                END IF
*
*             Update C := alpha*A'*A + beta*C, if TRANS = 'C'
*
              ELSE
                IF( ADATA ) THEN
                   CALL CGEMM( 'No', 'No', JNPBZ, LNW, K, TALPHA,
     $                         WORK(IPT), NP, A(1,JQBZ+1), LDA, TBETA,
     $                         C(1,JQBZ+1), LDC )
                ELSE
                   CALL CGEMM( 'No', 'No', JNPBZ, LNW, K, TALPHA,
     $                         WORK(IPT), NP, WORK(JQBZ*K+1), LKK,
     $                         TBETA, C(1,JQBZ+1), LDC )
                END IF
              END IF
*
*           Update data in the upper triangular matrix
*           and save data in the lower triangular matrix
*
            ELSE
*
*             Update C := alpha*A*A' + beta*C, if TRANS = 'N'
*
              IF( NOTRAN ) THEN
                IF( ADATA ) THEN
                  CALL CGEMM( 'No', 'No', JPBZ, LNW, K, TALPHA,
     $                        A, LDA, WORK(JQBZ*K+IPT), LKK, TBETA,
     $                        C(1,JQBZ+1), LDC )
                  CALL CGEMM( 'No', 'No', LMW, LNW, K, TALPHA,
     $                        A(JPBZ+1,1), LDA, WORK(JQBZ*K+IPT), LKK,
     $                        ZERO, WORK(IPW), MAX(1,LMW) )
                ELSE
                  CALL CGEMM( 'No', 'No', JPBZ, LNW, K, TALPHA,
     $                        WORK, NP, WORK(JQBZ*K+IPT), LKK, TBETA,
     $                        C(1,JQBZ+1), LDC )
                  CALL CGEMM( 'No', 'No', LMW, LNW, K, TALPHA,
     $                        WORK(JPBZ+1), NP, WORK(JQBZ*K+IPT), LKK,
     $                        ZERO, WORK(IPW), MAX(1,LMW) )
                END IF
*
*             Update C := alpha*A'*A + beta*C, if TRANS = 'C'
*
              ELSE
                IF( ADATA ) THEN
                  CALL CGEMM( 'No', 'No', JPBZ, LNW, K, TALPHA,
     $                        WORK(IPT), NP, A(1,JQBZ+1), LDA,
     $                        TBETA, C(1,JQBZ+1), LDC )
                  CALL CGEMM( 'No', 'No', LMW, LNW, K, TALPHA,
     $                        WORK(JPBZ+IPT), NP, A(1,JQBZ+1), LDA,
     $                        ZERO, WORK(IPW), MAX(1,LMW) )
                ELSE
                  CALL CGEMM( 'No', 'No', JPBZ, LNW, K, TALPHA,
     $                        WORK(IPT), NP, WORK(JQBZ*K+1), LKK,
     $                        TBETA, C(1,JQBZ+1), LDC )
                  CALL CGEMM( 'No', 'No', LMW, LNW, K, TALPHA,
     $                        WORK(JPBZ+IPT), NP, WORK(JQBZ*K+1), LKK,
     $                        ZERO, WORK(IPW), MAX(1,LMW) )
                END IF
              END IF
*
*             Compute diagonal blocks.
*
              MZROW = MRROW
              MZCOL = MRCOL
              KI = 0
*
              DO 30 KJ = 0, LCMQ-1
   20            CONTINUE
                 IF( MZROW.LT.MZCOL ) THEN
                    MZROW = MZROW + NPROW
                    KI = KI + 1
                    GO TO 20
                 END IF
                 KIZ = KI * NB
                 KJZ = KJ * NB
                 IF( KJZ.GE.LNW )
     $              GO TO 40
                 FORM = 'G'
                 IF( MZROW.EQ.MZCOL )
     $              FORM = 'H'
                 MZCOL = MZCOL + NPCOL
*
                 CALL PBCTRADD( ICONTXT, 'Upper', FORM, KIZ, NB, ONE,
     $                          WORK( KJZ*LMW+IPW ), LMW, TBETA,
     $                          C( JPBZ+1, JQBZ+KJZ+1 ), LDC,
     $                          LPBZ, LQBZ, LMW, LNW-KJZ )
   30         CONTINUE
            END IF
*
            JPBZ = JNPBZ
            JQBZ = JQBZ + LNW
   40     CONTINUE
*
*       If C is a Hermitian lower triangular matrix,
*
        ELSE
*
          ISZCMP = ICEIL( MULLEN, LQBZ )
          IF( ISZCMP.LE.0 ) ISZCMP = 1
          IPBZ = ISZCMP * LPBZ
          IQBZ = ISZCMP * LQBZ
          JPBZ = 0
          JQBZ = 0
*
          DO 70 JJ = 1, ICEIL(NQ, IQBZ)
            LMW = MIN( IPBZ, MAX(NP-JPBZ, 0) )
            LNW = MIN( IQBZ, MAX(NQ-JQBZ, 0) )
            JNPBZ = JPBZ + LMW
*
*           Modify (change) data in the upper triangular part
*
            IF( CSPACE ) THEN
*
*             Update C := alpha*A*A' + beta*C, if TRANS = 'N'
*
              IF( NOTRAN ) THEN
                IF( ADATA ) THEN
                  CALL CGEMM( 'No', 'No', NP-JPBZ, LNW, K, TALPHA,
     $                        A(JPBZ+1,1), LDA, WORK(JQBZ*K+IPT), LKK,
     $                        TBETA, C(JPBZ+1,JQBZ+1), LDC )
                ELSE
                  CALL CGEMM( 'No', 'No', NP-JPBZ, LNW, K, TALPHA,
     $                        WORK(JPBZ+1), NP, WORK(JQBZ*K+IPT), LKK,
     $                        TBETA, C(JPBZ+1,JQBZ+1), LDC )
                END IF
*
*             Update C := alpha*A'*A + beta*C, if TRANS = 'C'
*
              ELSE
                IF( ADATA ) THEN
                  CALL CGEMM( 'No', 'No', NP-JPBZ, LNW, K, TALPHA,
     $                        WORK(JPBZ+IPT), NP, A(1,JQBZ+1), LDA,
     $                        TBETA, C(JPBZ+1,JQBZ+1), LDC )
                ELSE
                  CALL CGEMM( 'No', 'No', NP-JPBZ, LNW, K, TALPHA,
     $                        WORK(JPBZ+IPT), NP, WORK(JQBZ*K+1), LKK,
     $                        TBETA, C(JPBZ+1,JQBZ+1), LDC )
                END IF
              END IF
*
*           Update data in the lower triangular matrix
*           and save data in the upper triangular matrix
*
            ELSE
*
*             Update C := alpha*A*A' + beta*C, if TRANS = 'N'
*
              IF( NOTRAN ) THEN
                IF( ADATA ) THEN
                  CALL CGEMM( 'No', 'No', NP-JNPBZ, LNW, K, TALPHA,
     $                        A(JNPBZ+1,1), LDA, WORK(JQBZ*K+IPT), LKK,
     $                        TBETA, C(JNPBZ+1,JQBZ+1), LDC )
                  CALL CGEMM( 'No', 'No', LMW, LNW, K, TALPHA,
     $                        A(JPBZ+1,1), LDA, WORK(JQBZ*K+IPT), LKK,
     $                        ZERO, WORK(IPW), MAX(1,LMW) )
                ELSE
                  CALL CGEMM( 'No', 'No', NP-JNPBZ, LNW, K, TALPHA,
     $                        WORK(JNPBZ+1), NP, WORK(JQBZ*K+IPT), LKK,
     $                        TBETA, C(JNPBZ+1,JQBZ+1), LDC )
                  CALL CGEMM( 'No', 'No', LMW, LNW, K, TALPHA,
     $                        WORK(JPBZ+1), NP, WORK(JQBZ*K+IPT), LKK,
     $                        ZERO, WORK(IPW), MAX(1,LMW) )
                END IF
*
*             Update C := alpha*A'*A + beta*C, if TRANS = 'C'
*
              ELSE
                IF( ADATA ) THEN
                  CALL CGEMM( 'No', 'No', NP-JNPBZ, LNW, K, TALPHA,
     $                        WORK(JNPBZ+IPT), NP, A(1,JQBZ+1), LDA,
     $                        TBETA, C(JNPBZ+1,JQBZ+1), LDC )
                  CALL CGEMM( 'No', 'No', LMW, LNW, K, TALPHA,
     $                        WORK(JPBZ+IPT), NP, A(1,JQBZ+1), LDA,
     $                        ZERO, WORK(IPW), MAX(1,LMW) )
                ELSE
                  CALL CGEMM( 'No', 'No', NP-JNPBZ, LNW, K, TALPHA,
     $                        WORK(JNPBZ+IPT), NP, WORK(JQBZ*K+1), LKK,
     $                        TBETA, C(JNPBZ+1,JQBZ+1), LDC)
                  CALL CGEMM( 'No', 'No', LMW, LNW, K, TALPHA,
     $                        WORK(JPBZ+IPT), NP, WORK(JQBZ*K+1), LKK,
     $                        ZERO, WORK(IPW), MAX(1,LMW) )
                END IF
              END IF
*
*             Compute diagonal blocks.
*
              MZROW = MRROW
              MZCOL = MRCOL
              KI = 0
*
              DO 60 KJ = 0, LCMQ-1
   50            CONTINUE
                 IF( MZROW.LT.MZCOL ) THEN
                    MZROW = MZROW + NPROW
                    KI = KI + 1
                    GO TO 50
                 END IF
                 KIZ = KI * NB
                 KJZ = KJ * NB
                 IF( KJZ.GE.LNW )
     $              GO TO 70
                 FORM = 'G'
                 IF( MZROW.EQ.MZCOL )
     $              FORM = 'H'
                 MZCOL = MZCOL + NPCOL
*
                 CALL PBCTRADD( ICONTXT, 'Lower', FORM, KIZ, NB, ONE,
     $                          WORK( KJZ*LMW+IPW ), LMW, TBETA,
     $                          C( JPBZ+1, JQBZ+KJZ+1 ), LDC,
     $                          LPBZ, LQBZ, LMW, LNW-KJZ )
   60         CONTINUE
            END IF
*
            JPBZ = JNPBZ
            JQBZ = JQBZ + LNW
   70     CONTINUE
        END IF
*
* === If C is just a block ===
*
      ELSE
        IF( NOTRAN .AND. MYROW.EQ.ICROW ) THEN
*
*         Form  C := alpha * A * (A') + beta * C.
*                                            _
*                                           | |
*                                           | |
*            _             _____________    | |            _
*           |_| = alpha * |______A______| * (A') + beta * |_|
*            C                              | |            C
*                                           | |
*                                           |_|
*
          NQ = NUMROC( K, NB, MYCOL, IAPOS, NPCOL )
          CSPACE = LSAME( CWORK, 'Y' )
*
          IF( LDA.LT.MAX(1,N)                          ) THEN
            INFO = 10
          ELSE IF( LDC.LT.MAX(1,N) .AND. ( CSPACE .OR.
     $             ICCOL.EQ.MYCOL .OR. ICCOL.EQ.-1 )   ) THEN
            INFO = 13
          ELSE IF( IAPOS.LT.0  .OR. IAPOS.GE.NPCOL     ) THEN
            INFO = 14
          ELSE IF( ICROW.LT.0  .OR. ICROW.GE.NPROW     ) THEN
            INFO = 15
          ELSE IF( ICCOL.LT.-1 .OR. ICCOL.GE.NPCOL     ) THEN
            INFO = 16
          END IF
          IF( INFO.NE.0 ) GO TO 10
*
*         Compute C
*
          IF( MYCOL.EQ.ICCOL ) THEN
            CALL CHERK( UPLO, TRANS, N, NQ, ALPHA, A,LDA, BETA, C,LDC )
            CALL PBCT1CPY( UPLO, JJ, N, C, LDC, WORK )
            CALL CGSUM2D( ICONTXT, 'Row', '1-tree', 1, JJ, WORK, 1,
     $                    ICROW, ICCOL )
            CALL PBCT2CPY( UPLO, JJ, N, C, LDC, WORK )
*
          ELSE
            IF( LSAME( CWORK, 'Y' ) ) THEN
              CALL CHERK( UPLO, TRANS, N, NQ, ALPHA, A, LDA, RZERO,
     $                    C, LDC )
              CALL PBCT1CPY( UPLO, JJ, N, C, LDC, WORK )
              CALL CGSUM2D( ICONTXT, 'Row', '1-tree', 1, JJ, WORK, 1,
     $                      ICROW, ICCOL )
            ELSE
              CALL CHERK( UPLO, TRANS, N, NQ, ALPHA, A, LDA, RZERO,
     $                    WORK, N )
              CALL PBCT3CPY( UPLO, JJ, N, WORK )
              CALL CGSUM2D( ICONTXT, 'Row', '1-tree', 1, JJ, WORK, 1,
     $                      ICROW, ICCOL )
            END IF
          END IF
*
        ELSE IF( LSAME( TRANS, 'C' ) .AND. MYCOL.EQ.ICCOL ) THEN
*
*         Form  B := alpha*B / op( A ).
*                                            _
*                                           | |
*                                           | |
*            _             _____________    | |           _
*           |_| = alpha * |_____(A')____| * |A| + beta * |_|
*            C                              | |           C
*                                           | |
*                                           |_|
*
          NP = NUMROC( K, NB, MYROW, IAPOS, NPROW )
          CSPACE = LSAME( CWORK, 'Y' )
*
          IF( LDA.LT.MAX(1,NP)                         ) THEN
            INFO = 10
          ELSE IF( LDC.LT.MAX(1,N) .AND. ( CSPACE .OR.
     $             ICROW.EQ.MYROW .OR. ICROW.EQ.-1 )   ) THEN
            INFO = 13
          ELSE IF( IAPOS.LT.0  .OR. IAPOS.GE.NPROW     ) THEN
            INFO = 14
          ELSE IF( ICROW.LT.-1 .OR. ICROW.GE.NPROW     ) THEN
            INFO = 15
          ELSE IF( ICCOL.LT.0  .OR. ICCOL.GE.NPCOL     ) THEN
            INFO = 16
          END IF
          IF( INFO.NE.0 ) GO TO 10
*
*         Compute C
*
          IF( MYROW.EQ.ICROW ) THEN
            CALL CHERK( UPLO, TRANS, N, NP, ALPHA, A,LDA, BETA, C,LDC )
            CALL PBCT1CPY( UPLO, JJ, N, C, LDC, WORK )
            CALL CGSUM2D( ICONTXT, 'Col', '1-tree', 1, JJ, WORK, 1,
     $                    ICROW, ICCOL )
            CALL PBCT2CPY( UPLO, JJ, N, C, LDC, WORK )
*
          ELSE
            IF( LSAME( CWORK, 'Y' ) ) THEN
              CALL CHERK( UPLO, TRANS, N, NP, ALPHA, A, LDA, RZERO,
     $                    C, LDC )
              CALL PBCT1CPY( UPLO, JJ, N, C, LDC, WORK )
              CALL CGSUM2D( ICONTXT, 'Col', '1-tree', 1, JJ, WORK, 1,
     $                      ICROW, ICCOL )
            ELSE
              CALL CHERK( UPLO, TRANS, N, NP, ALPHA, A, LDA, RZERO,
     $                    WORK, N )
              CALL PBCT3CPY( UPLO, JJ, N, WORK )
              CALL CGSUM2D( ICONTXT, 'Col', '1-tree', 1, JJ, WORK, 1,
     $                      ICROW, ICCOL )
            END IF
          END IF
        END IF
      END IF
*
      RETURN
*
*     End of PBCHERK
*
      END