      SUBROUTINE ZCHKTB( DOTYPE, NN, NVAL, NNS, NSVAL, THRESH, TSTERR,
     $                   NMAX, AB, AINV, B, X, XACT, WORK, RWORK, NOUT )
*
*  -- LAPACK test routine (version 3.0) --
*     Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
*     Courant Institute, Argonne National Lab, and Rice University
*     December 3, 1999
*
*     .. Scalar Arguments ..
      LOGICAL            TSTERR
      INTEGER            NMAX, NN, NNS, NOUT
      DOUBLE PRECISION   THRESH
*     ..
*     .. Array Arguments ..
      LOGICAL            DOTYPE( * )
      INTEGER            NSVAL( * ), NVAL( * )
      DOUBLE PRECISION   RWORK( * )
      COMPLEX*16         AB( * ), AINV( * ), B( * ), WORK( * ), X( * ),
     $                   XACT( * )
*     ..
*
*  Purpose
*  =======
*
*  ZCHKTB tests ZTBTRS, -RFS, and -CON, and ZLATBS.
*
*  Arguments
*  =========
*
*  DOTYPE  (input) LOGICAL array, dimension (NTYPES)
*          The matrix types to be used for testing.  Matrices of type j
*          (for 1 <= j <= NTYPES) are used for testing if DOTYPE(j) =
*          .TRUE.; if DOTYPE(j) = .FALSE., then type j is not used.
*
*  NN      (input) INTEGER
*          The number of values of N contained in the vector NVAL.
*
*  NVAL    (input) INTEGER array, dimension (NN)
*          The values of the matrix column dimension N.
*
*  NNS     (input) INTEGER
*          The number of values of NRHS contained in the vector NSVAL.
*
*  NSVAL   (input) INTEGER array, dimension (NNS)
*          The values of the number of right hand sides NRHS.
*
*  THRESH  (input) DOUBLE PRECISION
*          The threshold value for the test ratios.  A result is
*          included in the output file if RESULT >= THRESH.  To have
*          every test ratio printed, use THRESH = 0.
*
*  TSTERR  (input) LOGICAL
*          Flag that indicates whether error exits are to be tested.
*
*  NMAX    (input) INTEGER
*          The leading dimension of the work arrays.
*          NMAX >= the maximum value of N in NVAL.
*
*  AB      (workspace) COMPLEX*16 array, dimension (NMAX*NMAX)
*
*  AINV    (workspace) COMPLEX*16 array, dimension (NMAX*NMAX)
*
*  B       (workspace) COMPLEX*16 array, dimension (NMAX*NSMAX)
*          where NSMAX is the largest entry in NSVAL.
*
*  X       (workspace) COMPLEX*16 array, dimension (NMAX*NSMAX)
*
*  XACT    (workspace) COMPLEX*16 array, dimension (NMAX*NSMAX)
*
*  WORK    (workspace) COMPLEX*16 array, dimension
*                      (NMAX*max(3,NSMAX))
*
*  RWORK   (workspace) DOUBLE PRECISION array, dimension
*                      (max(NMAX,2*NSMAX))
*
*  NOUT    (input) INTEGER
*          The unit number for output.
*
*  =====================================================================
*
*     .. Parameters ..
      INTEGER            NTYPE1, NTYPES
      PARAMETER          ( NTYPE1 = 9, NTYPES = 17 )
      INTEGER            NTESTS
      PARAMETER          ( NTESTS = 8 )
      INTEGER            NTRAN
      PARAMETER          ( NTRAN = 3 )
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      CHARACTER          DIAG, NORM, TRANS, UPLO, XTYPE
      CHARACTER*3        PATH
      INTEGER            I, IDIAG, IK, IMAT, IN, INFO, IRHS, ITRAN,
     $                   IUPLO, J, K, KD, LDA, LDAB, N, NERRS, NFAIL,
     $                   NIMAT, NIMAT2, NK, NRHS, NRUN
      DOUBLE PRECISION   AINVNM, ANORM, RCOND, RCONDC, RCONDI, RCONDO,
     $                   SCALE
*     ..
*     .. Local Arrays ..
      CHARACTER          TRANSS( NTRAN ), UPLOS( 2 )
      INTEGER            ISEED( 4 ), ISEEDY( 4 )
      DOUBLE PRECISION   RESULT( NTESTS )
*     ..
*     .. External Functions ..
      LOGICAL            LSAME
      DOUBLE PRECISION   ZLANTB, ZLANTR
      EXTERNAL           LSAME, ZLANTB, ZLANTR
*     ..
*     .. External Subroutines ..
      EXTERNAL           ALAERH, ALAHD, ALASUM, ZCOPY, ZERRTR, ZGET04,
     $                   ZLACPY, ZLARHS, ZLASET, ZLATBS, ZLATTB, ZTBCON,
     $                   ZTBRFS, ZTBSV, ZTBT02, ZTBT03, ZTBT05, ZTBT06,
     $                   ZTBTRS
*     ..
*     .. Scalars in Common ..
      LOGICAL            LERR, OK
      CHARACTER*6        SRNAMT
      INTEGER            INFOT, IOUNIT
*     ..
*     .. Common blocks ..
      COMMON             / INFOC / INFOT, IOUNIT, OK, LERR
      COMMON             / SRNAMC / SRNAMT
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          DCMPLX, MAX, MIN
*     ..
*     .. Data statements ..
      DATA               ISEEDY / 1988, 1989, 1990, 1991 /
      DATA               UPLOS / 'U', 'L' / , TRANSS / 'N', 'T', 'C' /
*     ..
*     .. Executable Statements ..
*
*     Initialize constants and the random number seed.
*
      PATH( 1: 1 ) = 'Zomplex precision'
      PATH( 2: 3 ) = 'TB'
      NRUN = 0
      NFAIL = 0
      NERRS = 0
      DO 10 I = 1, 4
         ISEED( I ) = ISEEDY( I )
   10 CONTINUE
*
*     Test the error exits
*
      IF( TSTERR )
     $   CALL ZERRTR( PATH, NOUT )
      INFOT = 0
*
      DO 140 IN = 1, NN
*
*        Do for each value of N in NVAL
*
         N = NVAL( IN )
         LDA = MAX( 1, N )
         XTYPE = 'N'
         NIMAT = NTYPE1
         NIMAT2 = NTYPES
         IF( N.LE.0 ) THEN
            NIMAT = 1
            NIMAT2 = NTYPE1 + 1
         END IF
*
         NK = MIN( N+1, 4 )
         DO 130 IK = 1, NK
*
*           Do for KD = 0, N, (3N-1)/4, and (N+1)/4. This order makes
*           it easier to skip redundant values for small values of N.
*
            IF( IK.EQ.1 ) THEN
               KD = 0
            ELSE IF( IK.EQ.2 ) THEN
               KD = MAX( N, 0 )
            ELSE IF( IK.EQ.3 ) THEN
               KD = ( 3*N-1 ) / 4
            ELSE IF( IK.EQ.4 ) THEN
               KD = ( N+1 ) / 4
            END IF
            LDAB = KD + 1
*
            DO 90 IMAT = 1, NIMAT
*
*              Do the tests only if DOTYPE( IMAT ) is true.
*
               IF( .NOT.DOTYPE( IMAT ) )
     $            GO TO 90
*
               DO 80 IUPLO = 1, 2
*
*                 Do first for UPLO = 'U', then for UPLO = 'L'
*
                  UPLO = UPLOS( IUPLO )
*
*                 Call ZLATTB to generate a triangular test matrix.
*
                  SRNAMT = 'ZLATTB'
                  CALL ZLATTB( IMAT, UPLO, 'No transpose', DIAG, ISEED,
     $                         N, KD, AB, LDAB, X, WORK, RWORK, INFO )
*
*                 Set IDIAG = 1 for non-unit matrices, 2 for unit.
*
                  IF( LSAME( DIAG, 'N' ) ) THEN
                     IDIAG = 1
                  ELSE
                     IDIAG = 2
                  END IF
*
*                 Form the inverse of A so we can get a good estimate
*                 of RCONDC = 1/(norm(A) * norm(inv(A))).
*
                  CALL ZLASET( 'Full', N, N, DCMPLX( ZERO ),
     $                         DCMPLX( ONE ), AINV, LDA )
                  IF( LSAME( UPLO, 'U' ) ) THEN
                     DO 20 J = 1, N
                        CALL ZTBSV( UPLO, 'No transpose', DIAG, J, KD,
     $                              AB, LDAB, AINV( ( J-1 )*LDA+1 ), 1 )
   20                CONTINUE
                  ELSE
                     DO 30 J = 1, N
                        CALL ZTBSV( UPLO, 'No transpose', DIAG, N-J+1,
     $                              KD, AB( ( J-1 )*LDAB+1 ), LDAB,
     $                              AINV( ( J-1 )*LDA+J ), 1 )
   30                CONTINUE
                  END IF
*
*                 Compute the 1-norm condition number of A.
*
                  ANORM = ZLANTB( '1', UPLO, DIAG, N, KD, AB, LDAB,
     $                    RWORK )
                  AINVNM = ZLANTR( '1', UPLO, DIAG, N, N, AINV, LDA,
     $                     RWORK )
                  IF( ANORM.LE.ZERO .OR. AINVNM.LE.ZERO ) THEN
                     RCONDO = ONE
                  ELSE
                     RCONDO = ( ONE / ANORM ) / AINVNM
                  END IF
*
*                 Compute the infinity-norm condition number of A.
*
                  ANORM = ZLANTB( 'I', UPLO, DIAG, N, KD, AB, LDAB,
     $                    RWORK )
                  AINVNM = ZLANTR( 'I', UPLO, DIAG, N, N, AINV, LDA,
     $                     RWORK )
                  IF( ANORM.LE.ZERO .OR. AINVNM.LE.ZERO ) THEN
                     RCONDI = ONE
                  ELSE
                     RCONDI = ( ONE / ANORM ) / AINVNM
                  END IF
*
                  DO 60 IRHS = 1, NNS
                     NRHS = NSVAL( IRHS )
                     XTYPE = 'N'
*
                     DO 50 ITRAN = 1, NTRAN
*
*                    Do for op(A) = A, A**T, or A**H.
*
                        TRANS = TRANSS( ITRAN )
                        IF( ITRAN.EQ.1 ) THEN
                           NORM = 'O'
                           RCONDC = RCONDO
                        ELSE
                           NORM = 'I'
                           RCONDC = RCONDI
                        END IF
*
*+    TEST 1
*                    Solve and compute residual for op(A)*x = b.
*
                        SRNAMT = 'ZLARHS'
                        CALL ZLARHS( PATH, XTYPE, UPLO, TRANS, N, N, KD,
     $                               IDIAG, NRHS, AB, LDAB, XACT, LDA,
     $                               B, LDA, ISEED, INFO )
                        XTYPE = 'C'
                        CALL ZLACPY( 'Full', N, NRHS, B, LDA, X, LDA )
*
                        SRNAMT = 'ZTBTRS'
                        CALL ZTBTRS( UPLO, TRANS, DIAG, N, KD, NRHS, AB,
     $                               LDAB, X, LDA, INFO )
*
*                    Check error code from ZTBTRS.
*
                        IF( INFO.NE.0 )
     $                     CALL ALAERH( PATH, 'ZTBTRS', INFO, 0,
     $                                  UPLO // TRANS // DIAG, N, N, KD,
     $                                  KD, NRHS, IMAT, NFAIL, NERRS,
     $                                  NOUT )
*
                        CALL ZTBT02( UPLO, TRANS, DIAG, N, KD, NRHS, AB,
     $                               LDAB, X, LDA, B, LDA, WORK, RWORK,
     $                               RESULT( 1 ) )
*
*+    TEST 2
*                    Check solution from generated exact solution.
*
                        CALL ZGET04( N, NRHS, X, LDA, XACT, LDA, RCONDC,
     $                               RESULT( 2 ) )
*
*+    TESTS 3, 4, and 5
*                    Use iterative refinement to improve the solution
*                    and compute error bounds.
*
                        SRNAMT = 'ZTBRFS'
                        CALL ZTBRFS( UPLO, TRANS, DIAG, N, KD, NRHS, AB,
     $                               LDAB, B, LDA, X, LDA, RWORK,
     $                               RWORK( NRHS+1 ), WORK,
     $                               RWORK( 2*NRHS+1 ), INFO )
*
*                    Check error code from ZTBRFS.
*
                        IF( INFO.NE.0 )
     $                     CALL ALAERH( PATH, 'ZTBRFS', INFO, 0,
     $                                  UPLO // TRANS // DIAG, N, N, KD,
     $                                  KD, NRHS, IMAT, NFAIL, NERRS,
     $                                  NOUT )
*
                        CALL ZGET04( N, NRHS, X, LDA, XACT, LDA, RCONDC,
     $                               RESULT( 3 ) )
                        CALL ZTBT05( UPLO, TRANS, DIAG, N, KD, NRHS, AB,
     $                               LDAB, B, LDA, X, LDA, XACT, LDA,
     $                               RWORK, RWORK( NRHS+1 ),
     $                               RESULT( 4 ) )
*
*                       Print information about the tests that did not
*                       pass the threshold.
*
                        DO 40 K = 1, 5
                           IF( RESULT( K ).GE.THRESH ) THEN
                              IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
     $                           CALL ALAHD( NOUT, PATH )
                              WRITE( NOUT, FMT = 9999 )UPLO, TRANS,
     $                           DIAG, N, KD, NRHS, IMAT, K, RESULT( K )
                              NFAIL = NFAIL + 1
                           END IF
   40                   CONTINUE
                        NRUN = NRUN + 5
   50                CONTINUE
   60             CONTINUE
*
*+    TEST 6
*                    Get an estimate of RCOND = 1/CNDNUM.
*
                  DO 70 ITRAN = 1, 2
                     IF( ITRAN.EQ.1 ) THEN
                        NORM = 'O'
                        RCONDC = RCONDO
                     ELSE
                        NORM = 'I'
                        RCONDC = RCONDI
                     END IF
                     SRNAMT = 'ZTBCON'
                     CALL ZTBCON( NORM, UPLO, DIAG, N, KD, AB, LDAB,
     $                            RCOND, WORK, RWORK, INFO )
*
*                    Check error code from ZTBCON.
*
                     IF( INFO.NE.0 )
     $                  CALL ALAERH( PATH, 'ZTBCON', INFO, 0,
     $                               NORM // UPLO // DIAG, N, N, KD, KD,
     $                               -1, IMAT, NFAIL, NERRS, NOUT )
*
                     CALL ZTBT06( RCOND, RCONDC, UPLO, DIAG, N, KD, AB,
     $                            LDAB, RWORK, RESULT( 6 ) )
*
*                    Print the test ratio if it is .GE. THRESH.
*
                     IF( RESULT( 6 ).GE.THRESH ) THEN
                        IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
     $                     CALL ALAHD( NOUT, PATH )
                        WRITE( NOUT, FMT = 9998 ) 'ZTBCON', NORM, UPLO,
     $                     DIAG, N, KD, IMAT, 6, RESULT( 6 )
                        NFAIL = NFAIL + 1
                     END IF
                     NRUN = NRUN + 1
   70             CONTINUE
   80          CONTINUE
   90       CONTINUE
*
*           Use pathological test matrices to test ZLATBS.
*
            DO 120 IMAT = NTYPE1 + 1, NIMAT2
*
*              Do the tests only if DOTYPE( IMAT ) is true.
*
               IF( .NOT.DOTYPE( IMAT ) )
     $            GO TO 120
*
               DO 110 IUPLO = 1, 2
*
*                 Do first for UPLO = 'U', then for UPLO = 'L'
*
                  UPLO = UPLOS( IUPLO )
                  DO 100 ITRAN = 1, NTRAN
*
*                    Do for op(A) = A, A**T, and A**H.
*
                     TRANS = TRANSS( ITRAN )
*
*                    Call ZLATTB to generate a triangular test matrix.
*
                     SRNAMT = 'ZLATTB'
                     CALL ZLATTB( IMAT, UPLO, TRANS, DIAG, ISEED, N, KD,
     $                            AB, LDAB, X, WORK, RWORK, INFO )
*
*+    TEST 7
*                    Solve the system op(A)*x = b
*
                     SRNAMT = 'ZLATBS'
                     CALL ZCOPY( N, X, 1, B, 1 )
                     CALL ZLATBS( UPLO, TRANS, DIAG, 'N', N, KD, AB,
     $                            LDAB, B, SCALE, RWORK, INFO )
*
*                    Check error code from ZLATBS.
*
                     IF( INFO.NE.0 )
     $                  CALL ALAERH( PATH, 'ZLATBS', INFO, 0,
     $                               UPLO // TRANS // DIAG // 'N', N, N,
     $                               KD, KD, -1, IMAT, NFAIL, NERRS,
     $                               NOUT )
*
                     CALL ZTBT03( UPLO, TRANS, DIAG, N, KD, 1, AB, LDAB,
     $                            SCALE, RWORK, ONE, B, LDA, X, LDA,
     $                            WORK, RESULT( 7 ) )
*
*+    TEST 8
*                    Solve op(A)*x = b again with NORMIN = 'Y'.
*
                     CALL ZCOPY( N, X, 1, B, 1 )
                     CALL ZLATBS( UPLO, TRANS, DIAG, 'Y', N, KD, AB,
     $                            LDAB, B, SCALE, RWORK, INFO )
*
*                    Check error code from ZLATBS.
*
                     IF( INFO.NE.0 )
     $                  CALL ALAERH( PATH, 'ZLATBS', INFO, 0,
     $                               UPLO // TRANS // DIAG // 'Y', N, N,
     $                               KD, KD, -1, IMAT, NFAIL, NERRS,
     $                               NOUT )
*
                     CALL ZTBT03( UPLO, TRANS, DIAG, N, KD, 1, AB, LDAB,
     $                            SCALE, RWORK, ONE, B, LDA, X, LDA,
     $                            WORK, RESULT( 8 ) )
*
*                    Print information about the tests that did not pass
*                    the threshold.
*
                     IF( RESULT( 7 ).GE.THRESH ) THEN
                        IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
     $                     CALL ALAHD( NOUT, PATH )
                        WRITE( NOUT, FMT = 9997 )'ZLATBS', UPLO, TRANS,
     $                     DIAG, 'N', N, KD, IMAT, 7, RESULT( 7 )
                        NFAIL = NFAIL + 1
                     END IF
                     IF( RESULT( 8 ).GE.THRESH ) THEN
                        IF( NFAIL.EQ.0 .AND. NERRS.EQ.0 )
     $                     CALL ALAHD( NOUT, PATH )
                        WRITE( NOUT, FMT = 9997 )'ZLATBS', UPLO, TRANS,
     $                     DIAG, 'Y', N, KD, IMAT, 8, RESULT( 8 )
                        NFAIL = NFAIL + 1
                     END IF
                     NRUN = NRUN + 2
  100             CONTINUE
  110          CONTINUE
  120       CONTINUE
  130    CONTINUE
  140 CONTINUE
*
*     Print a summary of the results.
*
      CALL ALASUM( PATH, NOUT, NFAIL, NRUN, NERRS )
*
 9999 FORMAT( ' UPLO=''', A1, ''', TRANS=''', A1, ''',
     $      DIAG=''', A1, ''', N=', I5, ', KD=', I5, ', NRHS=', I5,
     $      ', type ', I2, ', test(', I2, ')=', G12.5 )
 9998 FORMAT( 1X, A6, '( ''', A1, ''', ''', A1, ''', ''', A1, ''',',
     $      I5, ',', I5, ',  ... ), type ', I2, ', test(', I2, ')=',
     $      G12.5 )
 9997 FORMAT( 1X, A6, '( ''', A1, ''', ''', A1, ''', ''', A1, ''', ''',
     $      A1, ''',', I5, ',', I5, ', ...  ),  type ', I2, ', test(',
     $      I1, ')=', G12.5 )
      RETURN
*
*     End of ZCHKTB
*
      END
