1       SUBROUTINE SDRVGB( DOTYPE, NN, NVAL, NRHS, THRESH, TSTERR, A, LA,
  2      $                   AFB, LAFB, ASAV, B, BSAV, X, XACT, S, WORK,
  3      $                   RWORK, IWORK, NOUT )
  4 *
  5 *  -- LAPACK test routine (version 3.1) --
  6 *     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
  7 *     November 2006
  8 *
  9 *     .. Scalar Arguments ..
 10       LOGICAL            TSTERR
 11       INTEGER            LA, LAFB, NN, NOUT, NRHS
 12       REAL               THRESH
 13 *     ..
 14 *     .. Array Arguments ..
 15       LOGICAL            DOTYPE( * )
 16       INTEGER            IWORK( * ), NVAL( * )
 17       REAL               A( * ), AFB( * ), ASAV( * ), B( * ), BSAV( * ),
 18      $                   RWORK( * ), S( * ), WORK( * ), X( * ),
 19      $                   XACT( * )
 20 *     ..
 21 *
 22 *  Purpose
 23 *  =======
 24 *
 25 *  SDRVGB tests the driver routines SGBSV and -SVX.
 26 *
 27 *  Arguments
 28 *  =========
 29 *
 30 *  DOTYPE  (input) LOGICAL array, dimension (NTYPES)
 31 *          The matrix types to be used for testing.  Matrices of type j
 32 *          (for 1 <= j <= NTYPES) are used for testing if DOTYPE(j) =
 33 *          .TRUE.; if DOTYPE(j) = .FALSE., then type j is not used.
 34 *
 35 *  NN      (input) INTEGER
 36 *          The number of values of N contained in the vector NVAL.
 37 *
 38 *  NVAL    (input) INTEGER array, dimension (NN)
 39 *          The values of the matrix column dimension N.
 40 *
 41 *  NRHS    (input) INTEGER
 42 *          The number of right hand side vectors to be generated for
 43 *          each linear system.
 44 *
 45 *  THRESH  (input) REAL
 46 *          The threshold value for the test ratios.  A result is
 47 *          included in the output file if RESULT >= THRESH.  To have
 48 *          every test ratio printed, use THRESH = 0.
 49 *
 50 *  TSTERR  (input) LOGICAL
 51 *          Flag that indicates whether error exits are to be tested.
 52 *
 53 *  A       (workspace) REAL array, dimension (LA)
 54 *
 55 *  LA      (input) INTEGER
 56 *          The length of the array A.  LA >= (2*NMAX-1)*NMAX
 57 *          where NMAX is the largest entry in NVAL.
 58 *
 59 *  AFB     (workspace) REAL array, dimension (LAFB)
 60 *
 61 *  LAFB    (input) INTEGER
 62 *          The length of the array AFB.  LAFB >= (3*NMAX-2)*NMAX
 63 *          where NMAX is the largest entry in NVAL.
 64 *
 65 *  ASAV    (workspace) REAL array, dimension (LA)
 66 *
 67 *  B       (workspace) REAL array, dimension (NMAX*NRHS)
 68 *
 69 *  BSAV    (workspace) REAL array, dimension (NMAX*NRHS)
 70 *
 71 *  X       (workspace) REAL array, dimension (NMAX*NRHS)
 72 *
 73 *  XACT    (workspace) REAL array, dimension (NMAX*NRHS)
 74 *
 75 *  S       (workspace) REAL array, dimension (2*NMAX)
 76 *
 77 *  WORK    (workspace) REAL array, dimension
 78 *                      (NMAX*max(3,NRHS,NMAX))
 79 *
 80 *  RWORK   (workspace) REAL array, dimension
 81 *                      (max(NMAX,2*NRHS))
 82 *
 83 *  IWORK   (workspace) INTEGER array, dimension (2*NMAX)
 84 *
 85 *  NOUT    (input) INTEGER
 86 *          The unit number for output.
 87 *
 88 *  =====================================================================
 89 *
 90 *     .. Parameters ..
 91       REAL               ONE, ZERO
 92       PARAMETER          ( ONE = 1.0E+0, ZERO = 0.0E+0 )
 93       INTEGER            NTYPES
 94       PARAMETER          ( NTYPES = 8 )
 95       INTEGER            NTESTS
 96       PARAMETER          ( NTESTS = 7 )
 97       INTEGER            NTRAN
 98       PARAMETER          ( NTRAN = 3 )
 99 *     ..
100 *     .. Local Scalars ..
101       LOGICAL            EQUIL, NOFACT, PREFAC, TRFCON, ZEROT
102       CHARACTER          DIST, EQUED, FACT, TRANS, TYPE, XTYPE
103       CHARACTER*3        PATH
104       INTEGER            I, I1, I2, IEQUED, IFACT, IKL, IKU, IMAT, IN,
105      $                   INFO, IOFF, ITRAN, IZERO, J, K, K1, KL, KU,
106      $                   LDA, LDAFB, LDB, MODE, N, NB, NBMIN, NERRS,
107      $                   NFACT, NFAIL, NIMAT, NKL, NKU, NRUN, NT
108       REAL               AINVNM, AMAX, ANORM, ANORMI, ANORMO, ANRMPV,
109      $                   CNDNUM, COLCND, RCOND, RCONDC, RCONDI, RCONDO,
110      $                   ROLDC, ROLDI, ROLDO, ROWCND, RPVGRW
111 *     ..
112 *     .. Local Arrays ..
113       CHARACTER          EQUEDS( 4 ), FACTS( 3 ), TRANSS( NTRAN )
114       INTEGER            ISEED( 4 ), ISEEDY( 4 )
115       REAL               RESULT( NTESTS )
116 *     ..
117 *     .. External Functions ..
118       LOGICAL            LSAME
119       REAL               SGET06, SLAMCH, SLANGB, SLANGE, SLANTB
120       EXTERNAL           LSAME, SGET06, SLAMCH, SLANGB, SLANGE, SLANTB
121 *     ..
122 *     .. External Subroutines ..
123       EXTERNAL           ALADHD, ALAERH, ALASVM, SERRVX, SGBEQU, SGBSV,
124      $                   SGBSVX, SGBT01, SGBT02, SGBT05, SGBTRF, SGBTRS,
125      $                   SGET04, SLACPY, SLAQGB, SLARHS, SLASET, SLATB4,
126      $                   SLATMS, XLAENV
127 *     ..
128 *     .. Intrinsic Functions ..
129       INTRINSIC          ABSMAXMIN
130 *     ..
131 *     .. Scalars in Common ..
132       LOGICAL            LERR, OK
133       CHARACTER*32       SRNAMT
134       INTEGER            INFOT, NUNIT
135 *     ..
136 *     .. Common blocks ..
137       COMMON             / INFOC / INFOT, NUNIT, OK, LERR
138       COMMON             / SRNAMC / SRNAMT
139 *     ..
140 *     .. Data statements ..
141       DATA               ISEEDY / 1988198919901991 /
142       DATA               TRANSS / 'N''T''C' /
143       DATA               FACTS / 'F''N''E' /
144       DATA               EQUEDS / 'N''R''C''B' /
145 *     ..
146 *     .. Executable Statements ..
147 *
148 *     Initialize constants and the random number seed.
149 *
150       PATH( 11 ) = 'Single precision'
151       PATH( 23 ) = 'GB'
152       NRUN = 0
153       NFAIL = 0
154       NERRS = 0
155       DO 10 I = 14
156          ISEED( I ) = ISEEDY( I )
157    10 CONTINUE
158 *
159 *     Test the error exits
160 *
161       IF( TSTERR )
162      $   CALL SERRVX( PATH, NOUT )
163       INFOT = 0
164 *
165 *     Set the block size and minimum block size for testing.
166 *
167       NB = 1
168       NBMIN = 2
169       CALL XLAENV( 1, NB )
170       CALL XLAENV( 2, NBMIN )
171 *
172 *     Do for each value of N in NVAL
173 *
174       DO 150 IN = 1, NN
175          N = NVAL( IN )
176          LDB = MAX( N, 1 )
177          XTYPE = 'N'
178 *
179 *        Set limits on the number of loop iterations.
180 *
181          NKL = MAX1MIN( N, 4 ) )
182          IF( N.EQ.0 )
183      $      NKL = 1
184          NKU = NKL
185          NIMAT = NTYPES
186          IF( N.LE.0 )
187      $      NIMAT = 1
188 *
189          DO 140 IKL = 1, NKL
190 *
191 *           Do for KL = 0, N-1, (3N-1)/4, and (N+1)/4. This order makes
192 *           it easier to skip redundant values for small values of N.
193 *
194             IF( IKL.EQ.1 ) THEN
195                KL = 0
196             ELSE IF( IKL.EQ.2 ) THEN
197                KL = MAX( N-10 )
198             ELSE IF( IKL.EQ.3 ) THEN
199                KL = ( 3*N-1 ) / 4
200             ELSE IF( IKL.EQ.4 ) THEN
201                KL = ( N+1 ) / 4
202             END IF
203             DO 130 IKU = 1, NKU
204 *
205 *              Do for KU = 0, N-1, (3N-1)/4, and (N+1)/4. This order
206 *              makes it easier to skip redundant values for small
207 *              values of N.
208 *
209                IF( IKU.EQ.1 ) THEN
210                   KU = 0
211                ELSE IF( IKU.EQ.2 ) THEN
212                   KU = MAX( N-10 )
213                ELSE IF( IKU.EQ.3 ) THEN
214                   KU = ( 3*N-1 ) / 4
215                ELSE IF( IKU.EQ.4 ) THEN
216                   KU = ( N+1 ) / 4
217                END IF
218 *
219 *              Check that A and AFB are big enough to generate this
220 *              matrix.
221 *
222                LDA = KL + KU + 1
223                LDAFB = 2*KL + KU + 1
224                IF( LDA*N.GT.LA .OR. LDAFB*N.GT.LAFB ) THEN
225                   IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
226      $               CALL ALADHD( NOUT, PATH )
227                   IF( LDA*N.GT.LA ) THEN
228                      WRITE( NOUT, FMT = 9999 )LA, N, KL, KU,
229      $                  N*( KL+KU+1 )
230                      NERRS = NERRS + 1
231                   END IF
232                   IF( LDAFB*N.GT.LAFB ) THEN
233                      WRITE( NOUT, FMT = 9998 )LAFB, N, KL, KU,
234      $                  N*2*KL+KU+1 )
235                      NERRS = NERRS + 1
236                   END IF
237                   GO TO 130
238                END IF
239 *
240                DO 120 IMAT = 1, NIMAT
241 *
242 *                 Do the tests only if DOTYPE( IMAT ) is true.
243 *
244                   IF.NOT.DOTYPE( IMAT ) )
245      $               GO TO 120
246 *
247 *                 Skip types 2, 3, or 4 if the matrix is too small.
248 *
249                   ZEROT = IMAT.GE.2 .AND. IMAT.LE.4
250                   IF( ZEROT .AND. N.LT.IMAT-1 )
251      $               GO TO 120
252 *
253 *                 Set up parameters with SLATB4 and generate a
254 *                 test matrix with SLATMS.
255 *
256                   CALL SLATB4( PATH, IMAT, N, N, TYPE, KL, KU, ANORM,
257      $                         MODE, CNDNUM, DIST )
258                   RCONDC = ONE / CNDNUM
259 *
260                   SRNAMT = 'SLATMS'
261                   CALL SLATMS( N, N, DIST, ISEED, TYPE, RWORK, MODE,
262      $                         CNDNUM, ANORM, KL, KU, 'Z', A, LDA, WORK,
263      $                         INFO )
264 *
265 *                 Check the error code from SLATMS.
266 *
267                   IF( INFO.NE.0 ) THEN
268                      CALL ALAERH( PATH, 'SLATMS', INFO, 0' ', N, N,
269      $                            KL, KU, -1, IMAT, NFAIL, NERRS, NOUT )
270                      GO TO 120
271                   END IF
272 *
273 *                 For types 2, 3, and 4, zero one or more columns of
274 *                 the matrix to test that INFO is returned correctly.
275 *
276                   IZERO = 0
277                   IF( ZEROT ) THEN
278                      IF( IMAT.EQ.2 ) THEN
279                         IZERO = 1
280                      ELSE IF( IMAT.EQ.3 ) THEN
281                         IZERO = N
282                      ELSE
283                         IZERO = N / 2 + 1
284                      END IF
285                      IOFF = ( IZERO-1 )*LDA
286                      IF( IMAT.LT.4 ) THEN
287                         I1 = MAX1, KU+2-IZERO )
288                         I2 = MIN( KL+KU+1, KU+1+( N-IZERO ) )
289                         DO 20 I = I1, I2
290                            A( IOFF+I ) = ZERO
291    20                   CONTINUE
292                      ELSE
293                         DO 40 J = IZERO, N
294                            DO 30 I = MAX1, KU+2-J ),
295      $                             MIN( KL+KU+1, KU+1+( N-J ) )
296                               A( IOFF+I ) = ZERO
297    30                      CONTINUE
298                            IOFF = IOFF + LDA
299    40                   CONTINUE
300                      END IF
301                   END IF
302 *
303 *                 Save a copy of the matrix A in ASAV.
304 *
305                   CALL SLACPY( 'Full', KL+KU+1, N, A, LDA, ASAV, LDA )
306 *
307                   DO 110 IEQUED = 14
308                      EQUED = EQUEDS( IEQUED )
309                      IF( IEQUED.EQ.1 ) THEN
310                         NFACT = 3
311                      ELSE
312                         NFACT = 1
313                      END IF
314 *
315                      DO 100 IFACT = 1, NFACT
316                         FACT = FACTS( IFACT )
317                         PREFAC = LSAME( FACT, 'F' )
318                         NOFACT = LSAME( FACT, 'N' )
319                         EQUIL = LSAME( FACT, 'E' )
320 *
321                         IF( ZEROT ) THEN
322                            IF( PREFAC )
323      $                        GO TO 100
324                            RCONDO = ZERO
325                            RCONDI = ZERO
326 *
327                         ELSE IF.NOT.NOFACT ) THEN
328 *
329 *                          Compute the condition number for comparison
330 *                          with the value returned by SGESVX (FACT =
331 *                          'N' reuses the condition number from the
332 *                          previous iteration with FACT = 'F').
333 *
334                            CALL SLACPY( 'Full', KL+KU+1, N, ASAV, LDA,
335      $                                  AFB( KL+1 ), LDAFB )
336                            IF( EQUIL .OR. IEQUED.GT.1 ) THEN
337 *
338 *                             Compute row and column scale factors to
339 *                             equilibrate the matrix A.
340 *
341                               CALL SGBEQU( N, N, KL, KU, AFB( KL+1 ),
342      $                                     LDAFB, S, S( N+1 ), ROWCND,
343      $                                     COLCND, AMAX, INFO )
344                               IF( INFO.EQ.0 .AND. N.GT.0 ) THEN
345                                  IF( LSAME( EQUED, 'R' ) ) THEN
346                                     ROWCND = ZERO
347                                     COLCND = ONE
348                                  ELSE IF( LSAME( EQUED, 'C' ) ) THEN
349                                     ROWCND = ONE
350                                     COLCND = ZERO
351                                  ELSE IF( LSAME( EQUED, 'B' ) ) THEN
352                                     ROWCND = ZERO
353                                     COLCND = ZERO
354                                  END IF
355 *
356 *                                Equilibrate the matrix.
357 *
358                                  CALL SLAQGB( N, N, KL, KU, AFB( KL+1 ),
359      $                                        LDAFB, S, S( N+1 ),
360      $                                        ROWCND, COLCND, AMAX,
361      $                                        EQUED )
362                               END IF
363                            END IF
364 *
365 *                          Save the condition number of the
366 *                          non-equilibrated system for use in SGET04.
367 *
368                            IF( EQUIL ) THEN
369                               ROLDO = RCONDO
370                               ROLDI = RCONDI
371                            END IF
372 *
373 *                          Compute the 1-norm and infinity-norm of A.
374 *
375                            ANORMO = SLANGB( '1', N, KL, KU, AFB( KL+1 ),
376      $                              LDAFB, RWORK )
377                            ANORMI = SLANGB( 'I', N, KL, KU, AFB( KL+1 ),
378      $                              LDAFB, RWORK )
379 *
380 *                          Factor the matrix A.
381 *
382                            CALL SGBTRF( N, N, KL, KU, AFB, LDAFB, IWORK,
383      $                                  INFO )
384 *
385 *                          Form the inverse of A.
386 *
387                            CALL SLASET( 'Full', N, N, ZERO, ONE, WORK,
388      $                                  LDB )
389                            SRNAMT = 'SGBTRS'
390                            CALL SGBTRS( 'No transpose', N, KL, KU, N,
391      $                                  AFB, LDAFB, IWORK, WORK, LDB,
392      $                                  INFO )
393 *
394 *                          Compute the 1-norm condition number of A.
395 *
396                            AINVNM = SLANGE( '1', N, N, WORK, LDB,
397      $                              RWORK )
398                            IF( ANORMO.LE.ZERO .OR. AINVNM.LE.ZERO ) THEN
399                               RCONDO = ONE
400                            ELSE
401                               RCONDO = ( ONE / ANORMO ) / AINVNM
402                            END IF
403 *
404 *                          Compute the infinity-norm condition number
405 *                          of A.
406 *
407                            AINVNM = SLANGE( 'I', N, N, WORK, LDB,
408      $                              RWORK )
409                            IF( ANORMI.LE.ZERO .OR. AINVNM.LE.ZERO ) THEN
410                               RCONDI = ONE
411                            ELSE
412                               RCONDI = ( ONE / ANORMI ) / AINVNM
413                            END IF
414                         END IF
415 *
416                         DO 90 ITRAN = 1, NTRAN
417 *
418 *                          Do for each value of TRANS.
419 *
420                            TRANS = TRANSS( ITRAN )
421                            IF( ITRAN.EQ.1 ) THEN
422                               RCONDC = RCONDO
423                            ELSE
424                               RCONDC = RCONDI
425                            END IF
426 *
427 *                          Restore the matrix A.
428 *
429                            CALL SLACPY( 'Full', KL+KU+1, N, ASAV, LDA,
430      $                                  A, LDA )
431 *
432 *                          Form an exact solution and set the right hand
433 *                          side.
434 *
435                            SRNAMT = 'SLARHS'
436                            CALL SLARHS( PATH, XTYPE, 'Full', TRANS, N,
437      $                                  N, KL, KU, NRHS, A, LDA, XACT,
438      $                                  LDB, B, LDB, ISEED, INFO )
439                            XTYPE = 'C'
440                            CALL SLACPY( 'Full', N, NRHS, B, LDB, BSAV,
441      $                                  LDB )
442 *
443                            IF( NOFACT .AND. ITRAN.EQ.1 ) THEN
444 *
445 *                             --- Test SGBSV  ---
446 *
447 *                             Compute the LU factorization of the matrix
448 *                             and solve the system.
449 *
450                               CALL SLACPY( 'Full', KL+KU+1, N, A, LDA,
451      $                                     AFB( KL+1 ), LDAFB )
452                               CALL SLACPY( 'Full', N, NRHS, B, LDB, X,
453      $                                     LDB )
454 *
455                               SRNAMT = 'SGBSV '
456                               CALL SGBSV( N, KL, KU, NRHS, AFB, LDAFB,
457      $                                    IWORK, X, LDB, INFO )
458 *
459 *                             Check error code from SGBSV .
460 *
461                               IF( INFO.NE.IZERO )
462      $                           CALL ALAERH( PATH, 'SGBSV ', INFO,
463      $                                        IZERO, ' ', N, N, KL, KU,
464      $                                        NRHS, IMAT, NFAIL, NERRS,
465      $                                        NOUT )
466 *
467 *                             Reconstruct matrix from factors and
468 *                             compute residual.
469 *
470                               CALL SGBT01( N, N, KL, KU, A, LDA, AFB,
471      $                                     LDAFB, IWORK, WORK,
472      $                                     RESULT1 ) )
473                               NT = 1
474                               IF( IZERO.EQ.0 ) THEN
475 *
476 *                                Compute residual of the computed
477 *                                solution.
478 *
479                                  CALL SLACPY( 'Full', N, NRHS, B, LDB,
480      $                                        WORK, LDB )
481                                  CALL SGBT02( 'No transpose', N, N, KL,
482      $                                        KU, NRHS, A, LDA, X, LDB,
483      $                                        WORK, LDB, RESULT2 ) )
484 *
485 *                                Check solution from generated exact
486 *                                solution.
487 *
488                                  CALL SGET04( N, NRHS, X, LDB, XACT,
489      $                                        LDB, RCONDC, RESULT3 ) )
490                                  NT = 3
491                               END IF
492 *
493 *                             Print information about the tests that did
494 *                             not pass the threshold.
495 *
496                               DO 50 K = 1, NT
497                                  IFRESULT( K ).GE.THRESH ) THEN
498                                     IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
499      $                                 CALL ALADHD( NOUT, PATH )
500                                     WRITE( NOUT, FMT = 9997 )'SGBSV ',
501      $                                 N, KL, KU, IMAT, K, RESULT( K )
502                                     NFAIL = NFAIL + 1
503                                  END IF
504    50                         CONTINUE
505                               NRUN = NRUN + NT
506                            END IF
507 *
508 *                          --- Test SGBSVX ---
509 *
510                            IF.NOT.PREFAC )
511      $                        CALL SLASET( 'Full'2*KL+KU+1, N, ZERO,
512      $                                     ZERO, AFB, LDAFB )
513                            CALL SLASET( 'Full', N, NRHS, ZERO, ZERO, X,
514      $                                  LDB )
515                            IF( IEQUED.GT.1 .AND. N.GT.0 ) THEN
516 *
517 *                             Equilibrate the matrix if FACT = 'F' and
518 *                             EQUED = 'R', 'C', or 'B'.
519 *
520                               CALL SLAQGB( N, N, KL, KU, A, LDA, S,
521      $                                     S( N+1 ), ROWCND, COLCND,
522      $                                     AMAX, EQUED )
523                            END IF
524 *
525 *                          Solve the system and compute the condition
526 *                          number and error bounds using SGBSVX.
527 *
528                            SRNAMT = 'SGBSVX'
529                            CALL SGBSVX( FACT, TRANS, N, KL, KU, NRHS, A,
530      $                                  LDA, AFB, LDAFB, IWORK, EQUED,
531      $                                  S, S( N+1 ), B, LDB, X, LDB,
532      $                                  RCOND, RWORK, RWORK( NRHS+1 ),
533      $                                  WORK, IWORK( N+1 ), INFO )
534 *
535 *                          Check the error code from SGBSVX.
536 *
537                            IF( INFO.NE.IZERO )
538      $                        CALL ALAERH( PATH, 'SGBSVX', INFO, IZERO,
539      $                                     FACT // TRANS, N, N, KL, KU,
540      $                                     NRHS, IMAT, NFAIL, NERRS,
541      $                                     NOUT )
542 *
543 *                          Compare WORK(1) from SGBSVX with the computed
544 *                          reciprocal pivot growth factor RPVGRW
545 *
546                            IF( INFO.NE.0 ) THEN
547                               ANRMPV = ZERO
548                               DO 70 J = 1, INFO
549                                  DO 60 I = MAX( KU+2-J, 1 ),
550      $                                   MIN( N+KU+1-J, KL+KU+1 )
551                                     ANRMPV = MAX( ANRMPV,
552      $                                       ABS( A( I+( J-1 )*LDA ) ) )
553    60                            CONTINUE
554    70                         CONTINUE
555                               RPVGRW = SLANTB( 'M''U''N', INFO,
556      $                                 MIN( INFO-1, KL+KU ),
557      $                                 AFB( MAX1, KL+KU+2-INFO ) ),
558      $                                 LDAFB, WORK )
559                               IF( RPVGRW.EQ.ZERO ) THEN
560                                  RPVGRW = ONE
561                               ELSE
562                                  RPVGRW = ANRMPV / RPVGRW
563                               END IF
564                            ELSE
565                               RPVGRW = SLANTB( 'M''U''N', N, KL+KU,
566      $                                 AFB, LDAFB, WORK )
567                               IF( RPVGRW.EQ.ZERO ) THEN
568                                  RPVGRW = ONE
569                               ELSE
570                                  RPVGRW = SLANGB( 'M', N, KL, KU, A,
571      $                                    LDA, WORK ) / RPVGRW
572                               END IF
573                            END IF
574                            RESULT7 ) = ABS( RPVGRW-WORK( 1 ) ) /
575      $                                   MAX( WORK( 1 ), RPVGRW ) /
576      $                                   SLAMCH( 'E' )
577 *
578                            IF.NOT.PREFAC ) THEN
579 *
580 *                             Reconstruct matrix from factors and
581 *                             compute residual.
582 *
583                               CALL SGBT01( N, N, KL, KU, A, LDA, AFB,
584      $                                     LDAFB, IWORK, WORK,
585      $                                     RESULT1 ) )
586                               K1 = 1
587                            ELSE
588                               K1 = 2
589                            END IF
590 *
591                            IF( INFO.EQ.0 ) THEN
592                               TRFCON = .FALSE.
593 *
594 *                             Compute residual of the computed solution.
595 *
596                               CALL SLACPY( 'Full', N, NRHS, BSAV, LDB,
597      $                                     WORK, LDB )
598                               CALL SGBT02( TRANS, N, N, KL, KU, NRHS,
599      $                                     ASAV, LDA, X, LDB, WORK, LDB,
600      $                                     RESULT2 ) )
601 *
602 *                             Check solution from generated exact
603 *                             solution.
604 *
605                               IF( NOFACT .OR. ( PREFAC .AND.
606      $                            LSAME( EQUED, 'N' ) ) ) THEN
607                                  CALL SGET04( N, NRHS, X, LDB, XACT,
608      $                                        LDB, RCONDC, RESULT3 ) )
609                               ELSE
610                                  IF( ITRAN.EQ.1 ) THEN
611                                     ROLDC = ROLDO
612                                  ELSE
613                                     ROLDC = ROLDI
614                                  END IF
615                                  CALL SGET04( N, NRHS, X, LDB, XACT,
616      $                                        LDB, ROLDC, RESULT3 ) )
617                               END IF
618 *
619 *                             Check the error bounds from iterative
620 *                             refinement.
621 *
622                               CALL SGBT05( TRANS, N, KL, KU, NRHS, ASAV,
623      $                                     LDA, B, LDB, X, LDB, XACT,
624      $                                     LDB, RWORK, RWORK( NRHS+1 ),
625      $                                     RESULT4 ) )
626                            ELSE
627                               TRFCON = .TRUE.
628                            END IF
629 *
630 *                          Compare RCOND from SGBSVX with the computed
631 *                          value in RCONDC.
632 *
633                            RESULT6 ) = SGET06( RCOND, RCONDC )
634 *
635 *                          Print information about the tests that did
636 *                          not pass the threshold.
637 *
638                            IF.NOT.TRFCON ) THEN
639                               DO 80 K = K1, NTESTS
640                                  IFRESULT( K ).GE.THRESH ) THEN
641                                     IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
642      $                                 CALL ALADHD( NOUT, PATH )
643                                     IF( PREFAC ) THEN
644                                        WRITE( NOUT, FMT = 9995 )
645      $                                    'SGBSVX', FACT, TRANS, N, KL,
646      $                                    KU, EQUED, IMAT, K,
647      $                                    RESULT( K )
648                                     ELSE
649                                        WRITE( NOUT, FMT = 9996 )
650      $                                    'SGBSVX', FACT, TRANS, N, KL,
651      $                                    KU, IMAT, K, RESULT( K )
652                                     END IF
653                                     NFAIL = NFAIL + 1
654                                  END IF
655    80                         CONTINUE
656                               NRUN = NRUN + 7 - K1
657                            ELSE
658                               IFRESULT1 ).GE.THRESH .AND. .NOT.
659      $                            PREFAC ) THEN
660                                  IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
661      $                              CALL ALADHD( NOUT, PATH )
662                                  IF( PREFAC ) THEN
663                                     WRITE( NOUT, FMT = 9995 )'SGBSVX',
664      $                                 FACT, TRANS, N, KL, KU, EQUED,
665      $                                 IMAT, 1RESULT1 )
666                                  ELSE
667                                     WRITE( NOUT, FMT = 9996 )'SGBSVX',
668      $                                 FACT, TRANS, N, KL, KU, IMAT, 1,
669      $                                 RESULT1 )
670                                  END IF
671                                  NFAIL = NFAIL + 1
672                                  NRUN = NRUN + 1
673                               END IF
674                               IFRESULT6 ).GE.THRESH ) THEN
675                                  IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
676      $                              CALL ALADHD( NOUT, PATH )
677                                  IF( PREFAC ) THEN
678                                     WRITE( NOUT, FMT = 9995 )'SGBSVX',
679      $                                 FACT, TRANS, N, KL, KU, EQUED,
680      $                                 IMAT, 6RESULT6 )
681                                  ELSE
682                                     WRITE( NOUT, FMT = 9996 )'SGBSVX',
683      $                                 FACT, TRANS, N, KL, KU, IMAT, 6,
684      $                                 RESULT6 )
685                                  END IF
686                                  NFAIL = NFAIL + 1
687                                  NRUN = NRUN + 1
688                               END IF
689                               IFRESULT7 ).GE.THRESH ) THEN
690                                  IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
691      $                              CALL ALADHD( NOUT, PATH )
692                                  IF( PREFAC ) THEN
693                                     WRITE( NOUT, FMT = 9995 )'SGBSVX',
694      $                                 FACT, TRANS, N, KL, KU, EQUED,
695      $                                 IMAT, 7RESULT7 )
696                                  ELSE
697                                     WRITE( NOUT, FMT = 9996 )'SGBSVX',
698      $                                 FACT, TRANS, N, KL, KU, IMAT, 7,
699      $                                 RESULT7 )
700                                  END IF
701                                  NFAIL = NFAIL + 1
702                                  NRUN = NRUN + 1
703                               END IF
704 *
705                            END IF
706    90                   CONTINUE
707   100                CONTINUE
708   110             CONTINUE
709   120          CONTINUE
710   130       CONTINUE
711   140    CONTINUE
712   150 CONTINUE
713 *
714 *     Print a summary of the results.
715 *
716       CALL ALASVM( PATH, NOUT, NFAIL, NRUN, NERRS )
717 *
718  9999 FORMAT' *** In SDRVGB, LA=', I5, ' is too small for N=', I5,
719      $      ', KU=', I5, ', KL=', I5, / ' ==> Increase LA to at least ',
720      $      I5 )
721  9998 FORMAT' *** In SDRVGB, LAFB=', I5, ' is too small for N=', I5,
722      $      ', KU=', I5, ', KL=', I5, /
723      $      ' ==> Increase LAFB to at least ', I5 )
724  9997 FORMAT1X, A, ', N=', I5, ', KL=', I5, ', KU=', I5, ', type ',
725      $      I1, ', test(', I1, ')='G12.5 )
726  9996 FORMAT1X, A, '( ''', A1, ''',''', A1, ''',', I5, ',', I5, ',',
727      $      I5, ',...), type ', I1, ', test(', I1, ')='G12.5 )
728  9995 FORMAT1X, A, '( ''', A1, ''',''', A1, ''',', I5, ',', I5, ',',
729      $      I5, ',...), EQUED=''', A1, ''', type ', I1, ', test(', I1,
730      $      ')='G12.5 )
731 *
732       RETURN
733 *
734 *     End of SDRVGB
735 *
736       END