dtrsv.f

来自「基于Blas CLapck的.用过的人知道是干啥的」· F 代码 · 共 240 行

      SUBROUTINE DTRSV( UPLO, TRANS, DIAG, N, A, LDA, X, INCX )
*
*  -- Automatically Tuned Linear Algebra Software (ATLAS)
*     (C) Copyright 2000 All Rights Reserved
*
*  -- ATLAS routine -- F77 Interface -- Version 3.2 -- December 25, 2000
*
*  Author         : Antoine P. Petitet
*  Originally developed at the University of Tennessee,
*  Innovative Computing Laboratory,  Knoxville TN, 37996-1301, USA.
*
*  ---------------------------------------------------------------------
*
*  -- Copyright notice and Licensing terms:
*
*  Redistribution  and  use in  source and binary forms, with or without
*  modification, are  permitted provided  that the following  conditions
*  are met:
*
*  1. Redistributions  of  source  code  must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*  2. Redistributions in binary form must reproduce  the above copyright
*     notice,  this list of conditions, and the  following disclaimer in
*     the documentation and/or other materials provided with the distri-
*     bution.
*  3. The name of the University,  the ATLAS group,  or the names of its
*     contributors  may not be used to endorse or promote products deri-
*     ved from this software without specific written permission.
*
*  -- Disclaimer:
*
*  THIS  SOFTWARE  IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
*  ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,  INCLUDING,  BUT NOT
*  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
*  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY
*  OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,  INDIRECT, INCIDENTAL, SPE-
*  CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
*  TO,  PROCUREMENT  OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
*  OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEO-
*  RY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT  (IN-
*  CLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
*  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*  ---------------------------------------------------------------------
*
*     .. Scalar Arguments ..
      CHARACTER*1        DIAG, TRANS, UPLO
      INTEGER            INCX, LDA, N
*     ..
*     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * ), X( * )
*     ..
*
*  Purpose
*  =======
*
*  DTRSV solves one of the systems of equations
*
*     A*x = b,   or   A'*x = b,
*
*  where b and x are n-element vectors and  A is an n by n unit, or non-
*  unit, upper or lower triangular matrix.
*
*  No test for  singularity  or  near-singularity  is included  in  this
*  routine. Such tests must be performed before calling this routine.
*
*  Arguments
*  =========
*
*  UPLO    (input)                       CHARACTER*1
*          On entry, UPLO  specifies whether  the  matrix is an upper or
*          lower triangular matrix as follows:
*
*              UPLO = 'U' or 'u'   A is an upper triangular matrix.
*
*              UPLO = 'L' or 'l'   A is a lower triangular matrix.
*
*          Unchanged on exit.
*
*  TRANS   (input)                       CHARACTER*1.
*          On entry,  TRANS specifies the equations to be solved as fol-
*          lows:
*
*             TRANS = 'N' or 'n'   A *x = b,
*
*             TRANS = 'T' or 't'   A'*x = b,
*
*             TRANS = 'T' or 't'   A'*x = b.
*
*          Unchanged on exit.
*
*  DIAG    (input)                       CHARACTER*1
*          On entry, DIAG specifies whether or not A is unit triangu-
*          lar as follows:
*
*             DIAG = 'U' or 'u'   A is assumed to be unit triangular.
*
*             DIAG = 'N' or 'n'   A is not assumed to be unit
*                                 triangular.
*
*          Unchanged on exit.
*
*  N       (input)                       INTEGER
*          On entry, N specifies the order of the matrix A. N must be at
*          least zero. Unchanged on exit.
*
*  A       (input)                       DOUBLE PRECISION array
*          On entry, A is an array of dimension ( LDA, n ). Before entry
*          with  UPLO = 'U' or 'u',  the leading n by n upper triangular
*          part of the array A must contain the upper triangular  matrix
*          and the strictly lower triangular part of  A  is not referen-
*          ced. Before entry with UPLO = 'L' or 'l', the leading  n by n
*          lower triangular part of the array  A  must contain the lower
*          triangular matrix and the strictly upper triangular part of A
*          is not referenced.
*          Note that when  DIAG = 'U' or 'u', the diagonal elements of A
*          are not referenced  either,  but are assumed to be unity. Un-
*          changed on exit.
*
*  LDA     (input)                       INTEGER
*          On entry, LDA  specifies the first dimension of A as declared
*          in the calling (sub) program. LDA must be at least  max(1,n).
*          Unchanged on exit.
*
*  X       (input/output)                DOUBLE PRECISION array
*          On entry,  X  is an incremented array of dimension  at  least
*          ( 1 + ( n - 1 ) * abs( INCX ) ).  Before entry, the incremen-
*          ted array X must contain the n element right-hand side vector
*          b. On exit, X is overwritten with the solution vector x.
*
*  INCX    (input)                       INTEGER
*          On entry, INCX specifies the increment for the elements of X.
*          INCX must not be zero. Unchanged on exit.
*
*  Further Details
*  ===============
*
*  For further information on the Level 1 BLAS specification, see:
*
*  ``A Proposal for Standard Linear Algebra Subprograms''  by R. Hanson,
*  F. Krogh and C. Lawson, ACM SIGNUM Newsl., 8(16), 1973,
*
*  ``Basic Linear Algebra Subprograms for Fortran Usage''  by C. Lawson,
*  R. Hanson, D. Kincaid and F. Krogh,  ACM Transactions on Mathematical
*  Software, 5(3) pp 308-323, 1979.
*
*  For further information on the Level 2 BLAS specification, see:
*
*  ``An  Extended Set of  FORTRAN  Basic Linear Algebra Subprograms'' by
*  J. Dongarra,  J. Du Croz,  S. Hammarling and R. Hanson,  ACM Transac-
*  tions on Mathematical Software, 14(1) pp 1-17, 1988.
*
*  ``Algorithm 656: An extended Set of Basic Linear Algebra Subprograms:
*  Model Implementation and Test Programs''  by J. Dongarra, J. Du Croz,
*  S. Hammarling and R. Hanson,  ACM  Transactions on Mathematical Soft-
*  ware, 14(1) pp 18-32, 1988.
*
*  For further information on the Level 3 BLAS specification, see:
*
*  ``A Set of Level 3 Basic Linear Algebra Subprograms'' by J. Dongarra,
*  J. Du Croz, I. Duff and S. Hammarling, ACM Transactions on Mathemati-
*  cal Software, 16(1), pp 1-17, 1990.
*
*  =====================================================================
*
*     .. Parameters ..
      INTEGER            ILOWER, IUPPER
      PARAMETER          ( IUPPER = 121, ILOWER = 122 )
      INTEGER            ICOTRAN, INOTRAN, ITRAN
      PARAMETER          ( INOTRAN = 111, ITRAN = 112, ICOTRAN = 113 )
      INTEGER            INONUNIT, IUNIT
      PARAMETER          ( INONUNIT = 131, IUNIT = 132 )
*     ..
*     .. Local Scalars ..
      INTEGER            IDIAG, INFO, ITRANS, IUPLO
*     ..
*     .. External Subroutines ..
      EXTERNAL           ATL_F77WRAP_DTRSV, XERBLA
*     ..
*     .. External Functions ..
      EXTERNAL           LSAME
      LOGICAL            LSAME
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          MAX
*     ..
*     .. Executable Statements ..
*
      INFO = 0
*
      IF(      LSAME( UPLO , 'U' ) ) THEN
         IUPLO = IUPPER
      ELSE IF( LSAME( UPLO , 'L' ) ) THEN
         IUPLO = ILOWER
      ELSE IF( INFO.EQ.0 ) THEN
         INFO  = 1
      END IF
*
      IF(      LSAME( TRANS, 'N' ) ) THEN
         ITRANS = INOTRAN
      ELSE IF( LSAME( TRANS, 'T' ) ) THEN
         ITRANS = ITRAN
      ELSE IF( LSAME( TRANS, 'C' ) ) THEN
         ITRANS = ICOTRAN
      ELSE IF( INFO.EQ.0 ) THEN
         INFO   = 2
      END IF
*
      IF(      LSAME( DIAG , 'N' ) ) THEN
         IDIAG = INONUNIT
      ELSE IF( LSAME( DIAG , 'U' ) ) THEN
         IDIAG = IUNIT
      ELSE IF( INFO.EQ.0 ) THEN
         INFO  = 3
      END IF
*
      IF( INFO.EQ.0 ) THEN
         IF( N.LT.0 ) THEN
            INFO = 4
         ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
            INFO = 6
         ELSE IF( INCX.EQ.0 ) THEN
            INFO = 8
         END IF
      END IF
*
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DTRSV ', INFO )
         RETURN
      END IF
*
      CALL ATL_F77WRAP_DTRSV( IUPLO, ITRANS, IDIAG, N, A, LDA,
     $                        X, INCX )
*
      RETURN
*
*     End of DTRSV
*
      END