1*> \brief \b SCHKPT
2*
3*  =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6*            http://www.netlib.org/lapack/explore-html/
7*
8*  Definition:
9*  ===========
10*
11*       SUBROUTINE SCHKPT( DOTYPE, NN, NVAL, NNS, NSVAL, THRESH, TSTERR,
12*                          A, D, E, B, X, XACT, WORK, RWORK, NOUT )
13*
14*       .. Scalar Arguments ..
15*       LOGICAL            TSTERR
16*       INTEGER            NN, NNS, NOUT
17*       REAL               THRESH
18*       ..
19*       .. Array Arguments ..
20*       LOGICAL            DOTYPE( * )
21*       INTEGER            NSVAL( * ), NVAL( * )
22*       REAL               A( * ), B( * ), D( * ), E( * ), RWORK( * ),
23*      $                   WORK( * ), X( * ), XACT( * )
24*       ..
25*
26*
27*> \par Purpose:
28*  =============
29*>
30*> \verbatim
31*>
32*> SCHKPT tests SPTTRF, -TRS, -RFS, and -CON
33*> \endverbatim
34*
35*  Arguments:
36*  ==========
37*
38*> \param[in] DOTYPE
39*> \verbatim
40*>          DOTYPE is LOGICAL array, dimension (NTYPES)
41*>          The matrix types to be used for testing.  Matrices of type j
42*>          (for 1 <= j <= NTYPES) are used for testing if DOTYPE(j) =
43*>          .TRUE.; if DOTYPE(j) = .FALSE., then type j is not used.
44*> \endverbatim
45*>
46*> \param[in] NN
47*> \verbatim
48*>          NN is INTEGER
49*>          The number of values of N contained in the vector NVAL.
50*> \endverbatim
51*>
52*> \param[in] NVAL
53*> \verbatim
54*>          NVAL is INTEGER array, dimension (NN)
55*>          The values of the matrix dimension N.
56*> \endverbatim
57*>
58*> \param[in] NNS
59*> \verbatim
60*>          NNS is INTEGER
61*>          The number of values of NRHS contained in the vector NSVAL.
62*> \endverbatim
63*>
64*> \param[in] NSVAL
65*> \verbatim
66*>          NSVAL is INTEGER array, dimension (NNS)
67*>          The values of the number of right hand sides NRHS.
68*> \endverbatim
69*>
70*> \param[in] THRESH
71*> \verbatim
72*>          THRESH is REAL
73*>          The threshold value for the test ratios.  A result is
74*>          included in the output file if RESULT >= THRESH.  To have
75*>          every test ratio printed, use THRESH = 0.
76*> \endverbatim
77*>
78*> \param[in] TSTERR
79*> \verbatim
80*>          TSTERR is LOGICAL
81*>          Flag that indicates whether error exits are to be tested.
82*> \endverbatim
83*>
84*> \param[out] A
85*> \verbatim
86*>          A is REAL array, dimension (NMAX*2)
87*> \endverbatim
88*>
89*> \param[out] D
90*> \verbatim
91*>          D is REAL array, dimension (NMAX*2)
92*> \endverbatim
93*>
94*> \param[out] E
95*> \verbatim
96*>          E is REAL array, dimension (NMAX*2)
97*> \endverbatim
98*>
99*> \param[out] B
100*> \verbatim
101*>          B is REAL array, dimension (NMAX*NSMAX)
102*>          where NSMAX is the largest entry in NSVAL.
103*> \endverbatim
104*>
105*> \param[out] X
106*> \verbatim
107*>          X is REAL array, dimension (NMAX*NSMAX)
108*> \endverbatim
109*>
110*> \param[out] XACT
111*> \verbatim
112*>          XACT is REAL array, dimension (NMAX*NSMAX)
113*> \endverbatim
114*>
115*> \param[out] WORK
116*> \verbatim
117*>          WORK is REAL array, dimension
118*>                      (NMAX*max(3,NSMAX))
119*> \endverbatim
120*>
121*> \param[out] RWORK
122*> \verbatim
123*>          RWORK is REAL array, dimension
124*>                      (max(NMAX,2*NSMAX))
125*> \endverbatim
126*>
127*> \param[in] NOUT
128*> \verbatim
129*>          NOUT is INTEGER
130*>          The unit number for output.
131*> \endverbatim
132*
133*  Authors:
134*  ========
135*
136*> \author Univ. of Tennessee
137*> \author Univ. of California Berkeley
138*> \author Univ. of Colorado Denver
139*> \author NAG Ltd.
140*
141*> \ingroup single_lin
142*
143*  =====================================================================
144      SUBROUTINE SCHKPT( DOTYPE, NN, NVAL, NNS, NSVAL, THRESH, TSTERR,
145     $                   A, D, E, B, X, XACT, WORK, RWORK, NOUT )
146*
147*  -- LAPACK test routine --
148*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
149*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
150*
151*     .. Scalar Arguments ..
152      LOGICAL            TSTERR
153      INTEGER            NN, NNS, NOUT
154      REAL               THRESH
155*     ..
156*     .. Array Arguments ..
157      LOGICAL            DOTYPE( * )
158      INTEGER            NSVAL( * ), NVAL( * )
159      REAL               A( * ), B( * ), D( * ), E( * ), RWORK( * ),
160     $                   WORK( * ), X( * ), XACT( * )
161*     ..
162*
163*  =====================================================================
164*
165*     .. Parameters ..
166      REAL               ONE, ZERO
167      PARAMETER          ( ONE = 1.0E+0, ZERO = 0.0E+0 )
168      INTEGER            NTYPES
169      PARAMETER          ( NTYPES = 12 )
170      INTEGER            NTESTS
171      PARAMETER          ( NTESTS = 7 )
172*     ..
173*     .. Local Scalars ..
174      LOGICAL            ZEROT
175      CHARACTER          DIST, TYPE
176      CHARACTER*3        PATH
177      INTEGER            I, IA, IMAT, IN, INFO, IRHS, IX, IZERO, J, K,
178     $                   KL, KU, LDA, MODE, N, NERRS, NFAIL, NIMAT,
179     $                   NRHS, NRUN
180      REAL               AINVNM, ANORM, COND, DMAX, RCOND, RCONDC
181*     ..
182*     .. Local Arrays ..
183      INTEGER            ISEED( 4 ), ISEEDY( 4 )
184      REAL               RESULT( NTESTS ), Z( 3 )
185*     ..
186*     .. External Functions ..
187      INTEGER            ISAMAX
188      REAL               SASUM, SGET06, SLANST
189      EXTERNAL           ISAMAX, SASUM, SGET06, SLANST
190*     ..
191*     .. External Subroutines ..
192      EXTERNAL           ALAERH, ALAHD, ALASUM, SCOPY, SERRGT, SGET04,
193     $                   SLACPY, SLAPTM, SLARNV, SLATB4, SLATMS, SPTCON,
194     $                   SPTRFS, SPTT01, SPTT02, SPTT05, SPTTRF, SPTTRS,
195     $                   SSCAL
196*     ..
197*     .. Intrinsic Functions ..
198      INTRINSIC          ABS, MAX
199*     ..
200*     .. Scalars in Common ..
201      LOGICAL            LERR, OK
202      CHARACTER*32       SRNAMT
203      INTEGER            INFOT, NUNIT
204*     ..
205*     .. Common blocks ..
206      COMMON             / INFOC / INFOT, NUNIT, OK, LERR
207      COMMON             / SRNAMC / SRNAMT
208*     ..
209*     .. Data statements ..
210      DATA               ISEEDY / 0, 0, 0, 1 /
211*     ..
212*     .. Executable Statements ..
213*
214      PATH( 1: 1 ) = 'Single precision'
215      PATH( 2: 3 ) = 'PT'
216      NRUN = 0
217      NFAIL = 0
218      NERRS = 0
219      DO 10 I = 1, 4
220         ISEED( I ) = ISEEDY( I )
221   10 CONTINUE
222*
223*     Test the error exits
224*
225      IF( TSTERR )
226     $   CALL SERRGT( PATH, NOUT )
227      INFOT = 0
228*
229      DO 110 IN = 1, NN
230*
231*        Do for each value of N in NVAL.
232*
233         N = NVAL( IN )
234         LDA = MAX( 1, N )
235         NIMAT = NTYPES
236         IF( N.LE.0 )
237     $      NIMAT = 1
238*
239         DO 100 IMAT = 1, NIMAT
240*
241*           Do the tests only if DOTYPE( IMAT ) is true.
242*
243            IF( N.GT.0 .AND. .NOT.DOTYPE( IMAT ) )
244     $         GO TO 100
245*
246*           Set up parameters with SLATB4.
247*
248            CALL SLATB4( PATH, IMAT, N, N, TYPE, KL, KU, ANORM, MODE,
249     $                   COND, DIST )
250*
251            ZEROT = IMAT.GE.8 .AND. IMAT.LE.10
252            IF( IMAT.LE.6 ) THEN
253*
254*              Type 1-6:  generate a symmetric tridiagonal matrix of
255*              known condition number in lower triangular band storage.
256*
257               SRNAMT = 'SLATMS'
258               CALL SLATMS( N, N, DIST, ISEED, TYPE, RWORK, MODE, COND,
259     $                      ANORM, KL, KU, 'B', A, 2, WORK, INFO )
260*
261*              Check the error code from SLATMS.
262*
263               IF( INFO.NE.0 ) THEN
264                  CALL ALAERH( PATH, 'SLATMS', INFO, 0, ' ', N, N, KL,
265     $                         KU, -1, IMAT, NFAIL, NERRS, NOUT )
266                  GO TO 100
267               END IF
268               IZERO = 0
269*
270*              Copy the matrix to D and E.
271*
272               IA = 1
273               DO 20 I = 1, N - 1
274                  D( I ) = A( IA )
275                  E( I ) = A( IA+1 )
276                  IA = IA + 2
277   20          CONTINUE
278               IF( N.GT.0 )
279     $            D( N ) = A( IA )
280            ELSE
281*
282*              Type 7-12:  generate a diagonally dominant matrix with
283*              unknown condition number in the vectors D and E.
284*
285               IF( .NOT.ZEROT .OR. .NOT.DOTYPE( 7 ) ) THEN
286*
287*                 Let D and E have values from [-1,1].
288*
289                  CALL SLARNV( 2, ISEED, N, D )
290                  CALL SLARNV( 2, ISEED, N-1, E )
291*
292*                 Make the tridiagonal matrix diagonally dominant.
293*
294                  IF( N.EQ.1 ) THEN
295                     D( 1 ) = ABS( D( 1 ) )
296                  ELSE
297                     D( 1 ) = ABS( D( 1 ) ) + ABS( E( 1 ) )
298                     D( N ) = ABS( D( N ) ) + ABS( E( N-1 ) )
299                     DO 30 I = 2, N - 1
300                        D( I ) = ABS( D( I ) ) + ABS( E( I ) ) +
301     $                           ABS( E( I-1 ) )
302   30                CONTINUE
303                  END IF
304*
305*                 Scale D and E so the maximum element is ANORM.
306*
307                  IX = ISAMAX( N, D, 1 )
308                  DMAX = D( IX )
309                  CALL SSCAL( N, ANORM / DMAX, D, 1 )
310                  CALL SSCAL( N-1, ANORM / DMAX, E, 1 )
311*
312               ELSE IF( IZERO.GT.0 ) THEN
313*
314*                 Reuse the last matrix by copying back the zeroed out
315*                 elements.
316*
317                  IF( IZERO.EQ.1 ) THEN
318                     D( 1 ) = Z( 2 )
319                     IF( N.GT.1 )
320     $                  E( 1 ) = Z( 3 )
321                  ELSE IF( IZERO.EQ.N ) THEN
322                     E( N-1 ) = Z( 1 )
323                     D( N ) = Z( 2 )
324                  ELSE
325                     E( IZERO-1 ) = Z( 1 )
326                     D( IZERO ) = Z( 2 )
327                     E( IZERO ) = Z( 3 )
328                  END IF
329               END IF
330*
331*              For types 8-10, set one row and column of the matrix to
332*              zero.
333*
334               IZERO = 0
335               IF( IMAT.EQ.8 ) THEN
336                  IZERO = 1
337                  Z( 2 ) = D( 1 )
338                  D( 1 ) = ZERO
339                  IF( N.GT.1 ) THEN
340                     Z( 3 ) = E( 1 )
341                     E( 1 ) = ZERO
342                  END IF
343               ELSE IF( IMAT.EQ.9 ) THEN
344                  IZERO = N
345                  IF( N.GT.1 ) THEN
346                     Z( 1 ) = E( N-1 )
347                     E( N-1 ) = ZERO
348                  END IF
349                  Z( 2 ) = D( N )
350                  D( N ) = ZERO
351               ELSE IF( IMAT.EQ.10 ) THEN
352                  IZERO = ( N+1 ) / 2
353                  IF( IZERO.GT.1 ) THEN
354                     Z( 1 ) = E( IZERO-1 )
355                     E( IZERO-1 ) = ZERO
356                     Z( 3 ) = E( IZERO )
357                     E( IZERO ) = ZERO
358                  END IF
359                  Z( 2 ) = D( IZERO )
360                  D( IZERO ) = ZERO
361               END IF
362            END IF
363*
364            CALL SCOPY( N, D, 1, D( N+1 ), 1 )
365            IF( N.GT.1 )
366     $         CALL SCOPY( N-1, E, 1, E( N+1 ), 1 )
367*
368*+    TEST 1
369*           Factor A as L*D*L' and compute the ratio
370*              norm(L*D*L' - A) / (n * norm(A) * EPS )
371*
372            CALL SPTTRF( N, D( N+1 ), E( N+1 ), INFO )
373*
374*           Check error code from SPTTRF.
375*
376            IF( INFO.NE.IZERO ) THEN
377               CALL ALAERH( PATH, 'SPTTRF', INFO, IZERO, ' ', N, N, -1,
378     $                      -1, -1, IMAT, NFAIL, NERRS, NOUT )
379               GO TO 100
380            END IF
381*
382            IF( INFO.GT.0 ) THEN
383               RCONDC = ZERO
384               GO TO 90
385            END IF
386*
387            CALL SPTT01( N, D, E, D( N+1 ), E( N+1 ), WORK,
388     $                   RESULT( 1 ) )
389*
390*           Print the test ratio if greater than or equal to THRESH.
391*
392            IF( RESULT( 1 ).GE.THRESH ) THEN
393               IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
394     $            CALL ALAHD( NOUT, PATH )
395               WRITE( NOUT, FMT = 9999 )N, IMAT, 1, RESULT( 1 )
396               NFAIL = NFAIL + 1
397            END IF
398            NRUN = NRUN + 1
399*
400*           Compute RCONDC = 1 / (norm(A) * norm(inv(A))
401*
402*           Compute norm(A).
403*
404            ANORM = SLANST( '1', N, D, E )
405*
406*           Use SPTTRS to solve for one column at a time of inv(A),
407*           computing the maximum column sum as we go.
408*
409            AINVNM = ZERO
410            DO 50 I = 1, N
411               DO 40 J = 1, N
412                  X( J ) = ZERO
413   40          CONTINUE
414               X( I ) = ONE
415               CALL SPTTRS( N, 1, D( N+1 ), E( N+1 ), X, LDA, INFO )
416               AINVNM = MAX( AINVNM, SASUM( N, X, 1 ) )
417   50       CONTINUE
418            RCONDC = ONE / MAX( ONE, ANORM*AINVNM )
419*
420            DO 80 IRHS = 1, NNS
421               NRHS = NSVAL( IRHS )
422*
423*           Generate NRHS random solution vectors.
424*
425               IX = 1
426               DO 60 J = 1, NRHS
427                  CALL SLARNV( 2, ISEED, N, XACT( IX ) )
428                  IX = IX + LDA
429   60          CONTINUE
430*
431*           Set the right hand side.
432*
433               CALL SLAPTM( N, NRHS, ONE, D, E, XACT, LDA, ZERO, B,
434     $                      LDA )
435*
436*+    TEST 2
437*           Solve A*x = b and compute the residual.
438*
439               CALL SLACPY( 'Full', N, NRHS, B, LDA, X, LDA )
440               CALL SPTTRS( N, NRHS, D( N+1 ), E( N+1 ), X, LDA, INFO )
441*
442*           Check error code from SPTTRS.
443*
444               IF( INFO.NE.0 )
445     $            CALL ALAERH( PATH, 'SPTTRS', INFO, 0, ' ', N, N, -1,
446     $                         -1, NRHS, IMAT, NFAIL, NERRS, NOUT )
447*
448               CALL SLACPY( 'Full', N, NRHS, B, LDA, WORK, LDA )
449               CALL SPTT02( N, NRHS, D, E, X, LDA, WORK, LDA,
450     $                      RESULT( 2 ) )
451*
452*+    TEST 3
453*           Check solution from generated exact solution.
454*
455               CALL SGET04( N, NRHS, X, LDA, XACT, LDA, RCONDC,
456     $                      RESULT( 3 ) )
457*
458*+    TESTS 4, 5, and 6
459*           Use iterative refinement to improve the solution.
460*
461               SRNAMT = 'SPTRFS'
462               CALL SPTRFS( N, NRHS, D, E, D( N+1 ), E( N+1 ), B, LDA,
463     $                      X, LDA, RWORK, RWORK( NRHS+1 ), WORK, INFO )
464*
465*           Check error code from SPTRFS.
466*
467               IF( INFO.NE.0 )
468     $            CALL ALAERH( PATH, 'SPTRFS', INFO, 0, ' ', N, N, -1,
469     $                         -1, NRHS, IMAT, NFAIL, NERRS, NOUT )
470*
471               CALL SGET04( N, NRHS, X, LDA, XACT, LDA, RCONDC,
472     $                      RESULT( 4 ) )
473               CALL SPTT05( N, NRHS, D, E, B, LDA, X, LDA, XACT, LDA,
474     $                      RWORK, RWORK( NRHS+1 ), RESULT( 5 ) )
475*
476*           Print information about the tests that did not pass the
477*           threshold.
478*
479               DO 70 K = 2, 6
480                  IF( RESULT( K ).GE.THRESH ) THEN
481                     IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
482     $                  CALL ALAHD( NOUT, PATH )
483                     WRITE( NOUT, FMT = 9998 )N, NRHS, IMAT, K,
484     $                  RESULT( K )
485                     NFAIL = NFAIL + 1
486                  END IF
487   70          CONTINUE
488               NRUN = NRUN + 5
489   80       CONTINUE
490*
491*+    TEST 7
492*           Estimate the reciprocal of the condition number of the
493*           matrix.
494*
495   90       CONTINUE
496            SRNAMT = 'SPTCON'
497            CALL SPTCON( N, D( N+1 ), E( N+1 ), ANORM, RCOND, RWORK,
498     $                   INFO )
499*
500*           Check error code from SPTCON.
501*
502            IF( INFO.NE.0 )
503     $         CALL ALAERH( PATH, 'SPTCON', INFO, 0, ' ', N, N, -1, -1,
504     $                      -1, IMAT, NFAIL, NERRS, NOUT )
505*
506            RESULT( 7 ) = SGET06( RCOND, RCONDC )
507*
508*           Print the test ratio if greater than or equal to THRESH.
509*
510            IF( RESULT( 7 ).GE.THRESH ) THEN
511               IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
512     $            CALL ALAHD( NOUT, PATH )
513               WRITE( NOUT, FMT = 9999 )N, IMAT, 7, RESULT( 7 )
514               NFAIL = NFAIL + 1
515            END IF
516            NRUN = NRUN + 1
517  100    CONTINUE
518  110 CONTINUE
519*
520*     Print a summary of the results.
521*
522      CALL ALASUM( PATH, NOUT, NFAIL, NRUN, NERRS )
523*
524 9999 FORMAT( ' N =', I5, ', type ', I2, ', test ', I2, ', ratio = ',
525     $      G12.5 )
526 9998 FORMAT( ' N =', I5, ', NRHS=', I3, ', type ', I2, ', test(', I2,
527     $      ') = ', G12.5 )
528      RETURN
529*
530*     End of SCHKPT
531*
532      END
533