      SUBROUTINE DLARHS( PATH, XTYPE, UPLO, TRANS, M, N, KL, KU, NRHS,
     $                   A, LDA, X, LDX, B, LDB, ISEED, INFO )
*
*  -- LAPACK test routine (version 3.1) --
*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
*     November 2006
*
*     .. Scalar Arguments ..
      CHARACTER          TRANS, UPLO, XTYPE
      CHARACTER*3        PATH
      INTEGER            INFO, KL, KU, LDA, LDB, LDX, M, N, NRHS
*     ..
*     .. Array Arguments ..
      INTEGER            ISEED( 4 )
      DOUBLE PRECISION   A( LDA, * ), B( LDB, * ), X( LDX, * )
*     ..
*
*  Purpose
*  =======
*
*  DLARHS chooses a set of NRHS random solution vectors and sets
*  up the right hand sides for the linear system
*     op( A ) * X = B,
*  where op( A ) may be A or A' (transpose of A).
*
*  Arguments
*  =========
*
*  PATH    (input) CHARACTER*3
*          The type of the real matrix A.  PATH may be given in any
*          combination of upper and lower case.  Valid types include
*             xGE:  General m x n matrix
*             xGB:  General banded matrix
*             xPO:  Symmetric positive definite, 2-D storage
*             xPP:  Symmetric positive definite packed
*             xPB:  Symmetric positive definite banded
*             xSY:  Symmetric indefinite, 2-D storage
*             xSP:  Symmetric indefinite packed
*             xSB:  Symmetric indefinite banded
*             xTR:  Triangular
*             xTP:  Triangular packed
*             xTB:  Triangular banded
*             xQR:  General m x n matrix
*             xLQ:  General m x n matrix
*             xQL:  General m x n matrix
*             xRQ:  General m x n matrix
*          where the leading character indicates the precision.
*
*  XTYPE   (input) CHARACTER*1
*          Specifies how the exact solution X will be determined:
*          = 'N':  New solution; generate a random X.
*          = 'C':  Computed; use value of X on entry.
*
*  UPLO    (input) CHARACTER*1
*          Specifies whether the upper or lower triangular part of the
*          matrix A is stored, if A is symmetric.
*          = 'U':  Upper triangular
*          = 'L':  Lower triangular
*
*  TRANS   (input) CHARACTER*1
*          Specifies the operation applied to the matrix A.
*          = 'N':  System is  A * x = b
*          = 'T':  System is  A'* x = b
*          = 'C':  System is  A'* x = b
*
*  M       (input) INTEGER
*          The number or rows of the matrix A.  M >= 0.
*
*  N       (input) INTEGER
*          The number of columns of the matrix A.  N >= 0.
*
*  KL      (input) INTEGER
*          Used only if A is a band matrix; specifies the number of
*          subdiagonals of A if A is a general band matrix or if A is
*          symmetric or triangular and UPLO = 'L'; specifies the number
*          of superdiagonals of A if A is symmetric or triangular and
*          UPLO = 'U'.  0 <= KL <= M-1.
*
*  KU      (input) INTEGER
*          Used only if A is a general band matrix or if A is
*          triangular.
*
*          If PATH = xGB, specifies the number of superdiagonals of A,
*          and 0 <= KU <= N-1.
*
*          If PATH = xTR, xTP, or xTB, specifies whether or not the
*          matrix has unit diagonal:
*          = 1:  matrix has non-unit diagonal (default)
*          = 2:  matrix has unit diagonal
*
*  NRHS    (input) INTEGER
*          The number of right hand side vectors in the system A*X = B.
*
*  A       (input) DOUBLE PRECISION array, dimension (LDA,N)
*          The test matrix whose type is given by PATH.
*
*  LDA     (input) INTEGER
*          The leading dimension of the array A.
*          If PATH = xGB, LDA >= KL+KU+1.
*          If PATH = xPB, xSB, xHB, or xTB, LDA >= KL+1.
*          Otherwise, LDA >= max(1,M).
*
*  X       (input or output) DOUBLE PRECISION array, dimension(LDX,NRHS)
*          On entry, if XTYPE = 'C' (for 'Computed'), then X contains
*          the exact solution to the system of linear equations.
*          On exit, if XTYPE = 'N' (for 'New'), then X is initialized
*          with random values.
*
*  LDX     (input) INTEGER
*          The leading dimension of the array X.  If TRANS = 'N',
*          LDX >= max(1,N); if TRANS = 'T', LDX >= max(1,M).
*
*  B       (output) DOUBLE PRECISION array, dimension (LDB,NRHS)
*          The right hand side vector(s) for the system of equations,
*          computed from B = op(A) * X, where op(A) is determined by
*          TRANS.
*
*  LDB     (input) INTEGER
*          The leading dimension of the array B.  If TRANS = 'N',
*          LDB >= max(1,M); if TRANS = 'T', LDB >= max(1,N).
*
*  ISEED   (input/output) INTEGER array, dimension (4)
*          The seed vector for the random number generator (used in
*          DLATMS).  Modified on exit.
*
*  INFO    (output) INTEGER
*          = 0:  successful exit
*          < 0:  if INFO = -i, the i-th argument had an illegal value
*
*  =====================================================================
*
*     .. Parameters ..
      DOUBLE PRECISION   ONE, ZERO
      PARAMETER          ( ONE = 1.0D+0, ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      LOGICAL            BAND, GEN, NOTRAN, QRS, SYM, TRAN, TRI
      CHARACTER          C1, DIAG
      CHARACTER*2        C2
      INTEGER            J, MB, NX
*     ..
*     .. External Functions ..
      LOGICAL            LSAME, LSAMEN
      EXTERNAL           LSAME, LSAMEN
*     ..
*     .. External Subroutines ..
      EXTERNAL           DGBMV, DGEMM, DLACPY, DLARNV, DSBMV, DSPMV,
     $                   DSYMM, DTBMV, DTPMV, DTRMM, XERBLA
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX
*     ..
*     .. Executable Statements ..
*
*     Test the input parameters.
*
      INFO = 0
      C1 = PATH( 1: 1 )
      C2 = PATH( 2: 3 )
      TRAN = LSAME( TRANS, 'T' ) .OR. LSAME( TRANS, 'C' )
      NOTRAN = .NOT.TRAN
      GEN = LSAME( PATH( 2: 2 ), 'G' )
      QRS = LSAME( PATH( 2: 2 ), 'Q' ) .OR. LSAME( PATH( 3: 3 ), 'Q' )
      SYM = LSAME( PATH( 2: 2 ), 'P' ) .OR. LSAME( PATH( 2: 2 ), 'S' )
      TRI = LSAME( PATH( 2: 2 ), 'T' )
      BAND = LSAME( PATH( 3: 3 ), 'B' )
      IF( .NOT.LSAME( C1, 'Double precision' ) ) THEN
         INFO = -1
      ELSE IF( .NOT.( LSAME( XTYPE, 'N' ) .OR. LSAME( XTYPE, 'C' ) ) )
     $          THEN
         INFO = -2
      ELSE IF( ( SYM .OR. TRI ) .AND. .NOT.
     $         ( LSAME( UPLO, 'U' ) .OR. LSAME( UPLO, 'L' ) ) ) THEN
         INFO = -3
      ELSE IF( ( GEN .OR. QRS ) .AND. .NOT.
     $         ( TRAN .OR. LSAME( TRANS, 'N' ) ) ) THEN
         INFO = -4
      ELSE IF( M.LT.0 ) THEN
         INFO = -5
      ELSE IF( N.LT.0 ) THEN
         INFO = -6
      ELSE IF( BAND .AND. KL.LT.0 ) THEN
         INFO = -7
      ELSE IF( BAND .AND. KU.LT.0 ) THEN
         INFO = -8
      ELSE IF( NRHS.LT.0 ) THEN
         INFO = -9
      ELSE IF( ( .NOT.BAND .AND. LDA.LT.MAX( 1, M ) ) .OR.
     $         ( BAND .AND. ( SYM .OR. TRI ) .AND. LDA.LT.KL+1 ) .OR.
     $         ( BAND .AND. GEN .AND. LDA.LT.KL+KU+1 ) ) THEN
         INFO = -11
      ELSE IF( ( NOTRAN .AND. LDX.LT.MAX( 1, N ) ) .OR.
     $         ( TRAN .AND. LDX.LT.MAX( 1, M ) ) ) THEN
         INFO = -13
      ELSE IF( ( NOTRAN .AND. LDB.LT.MAX( 1, M ) ) .OR.
     $         ( TRAN .AND. LDB.LT.MAX( 1, N ) ) ) THEN
         INFO = -15
      END IF
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DLARHS', -INFO )
         RETURN
      END IF
*
*     Initialize X to NRHS random vectors unless XTYPE = 'C'.
*
      IF( TRAN ) THEN
         NX = M
         MB = N
      ELSE
         NX = N
         MB = M
      END IF
      IF( .NOT.LSAME( XTYPE, 'C' ) ) THEN
         DO 10 J = 1, NRHS
            CALL DLARNV( 2, ISEED, N, X( 1, J ) )
   10    CONTINUE
      END IF
*
*     Multiply X by op( A ) using an appropriate
*     matrix multiply routine.
*
      IF( LSAMEN( 2, C2, 'GE' ) .OR. LSAMEN( 2, C2, 'QR' ) .OR.
     $    LSAMEN( 2, C2, 'LQ' ) .OR. LSAMEN( 2, C2, 'QL' ) .OR.
     $    LSAMEN( 2, C2, 'RQ' ) ) THEN
*
*        General matrix
*
         CALL DGEMM( TRANS, 'N', MB, NRHS, NX, ONE, A, LDA, X, LDX,
     $               ZERO, B, LDB )
*
      ELSE IF( LSAMEN( 2, C2, 'PO' ) .OR. LSAMEN( 2, C2, 'SY' ) ) THEN
*
*        Symmetric matrix, 2-D storage
*
         CALL DSYMM( 'Left', UPLO, N, NRHS, ONE, A, LDA, X, LDX, ZERO,
     $               B, LDB )
*
      ELSE IF( LSAMEN( 2, C2, 'GB' ) ) THEN
*
*        General matrix, band storage
*
         DO 20 J = 1, NRHS
            CALL DGBMV( TRANS, MB, NX, KL, KU, ONE, A, LDA, X( 1, J ),
     $                  1, ZERO, B( 1, J ), 1 )
   20    CONTINUE
*
      ELSE IF( LSAMEN( 2, C2, 'PB' ) ) THEN
*
*        Symmetric matrix, band storage
*
         DO 30 J = 1, NRHS
            CALL DSBMV( UPLO, N, KL, ONE, A, LDA, X( 1, J ), 1, ZERO,
     $                  B( 1, J ), 1 )
   30    CONTINUE
*
      ELSE IF( LSAMEN( 2, C2, 'PP' ) .OR. LSAMEN( 2, C2, 'SP' ) ) THEN
*
*        Symmetric matrix, packed storage
*
         DO 40 J = 1, NRHS
            CALL DSPMV( UPLO, N, ONE, A, X( 1, J ), 1, ZERO, B( 1, J ),
     $                  1 )
   40    CONTINUE
*
      ELSE IF( LSAMEN( 2, C2, 'TR' ) ) THEN
*
*        Triangular matrix.  Note that for triangular matrices,
*           KU = 1 => non-unit triangular
*           KU = 2 => unit triangular
*
         CALL DLACPY( 'Full', N, NRHS, X, LDX, B, LDB )
         IF( KU.EQ.2 ) THEN
            DIAG = 'U'
         ELSE
            DIAG = 'N'
         END IF
         CALL DTRMM( 'Left', UPLO, TRANS, DIAG, N, NRHS, ONE, A, LDA, B,
     $               LDB )
*
      ELSE IF( LSAMEN( 2, C2, 'TP' ) ) THEN
*
*        Triangular matrix, packed storage
*
         CALL DLACPY( 'Full', N, NRHS, X, LDX, B, LDB )
         IF( KU.EQ.2 ) THEN
            DIAG = 'U'
         ELSE
            DIAG = 'N'
         END IF
         DO 50 J = 1, NRHS
            CALL DTPMV( UPLO, TRANS, DIAG, N, A, B( 1, J ), 1 )
   50    CONTINUE
*
      ELSE IF( LSAMEN( 2, C2, 'TB' ) ) THEN
*
*        Triangular matrix, banded storage
*
         CALL DLACPY( 'Full', N, NRHS, X, LDX, B, LDB )
         IF( KU.EQ.2 ) THEN
            DIAG = 'U'
         ELSE
            DIAG = 'N'
         END IF
         DO 60 J = 1, NRHS
            CALL DTBMV( UPLO, TRANS, DIAG, N, KL, A, LDA, B( 1, J ), 1 )
   60    CONTINUE
*
      ELSE
*
*        If PATH is none of the above, return with an error code.
*
         INFO = -1
         CALL XERBLA( 'DLARHS', -INFO )
      END IF
*
      RETURN
*
*     End of DLARHS
*
      END
