• NAME
• SYNOPSIS
• F95 INTERFACE
• C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

dtrsm - solve one of the matrix equations op( A )*X = alpha*B, or X*op( A ) = alpha*B

SYNOPSIS

  SUBROUTINE DTRSM( SIDE, UPLO, TRANSA, DIAG, M, N, ALPHA, A, LDA, B, 
 *      LDB)
  CHARACTER * 1 SIDE, UPLO, TRANSA, DIAG
  INTEGER M, N, LDA, LDB
  DOUBLE PRECISION ALPHA
  DOUBLE PRECISION A(LDA,*), B(LDB,*)

  SUBROUTINE DTRSM_64( SIDE, UPLO, TRANSA, DIAG, M, N, ALPHA, A, LDA, 
 *      B, LDB)
  CHARACTER * 1 SIDE, UPLO, TRANSA, DIAG
  INTEGER*8 M, N, LDA, LDB
  DOUBLE PRECISION ALPHA
  DOUBLE PRECISION A(LDA,*), B(LDB,*)

F95 INTERFACE

  SUBROUTINE TRSM( SIDE, UPLO, [TRANSA], DIAG, [M], [N], ALPHA, A, 
 *       [LDA], B, [LDB])
  CHARACTER(LEN=1) :: SIDE, UPLO, TRANSA, DIAG
  INTEGER :: M, N, LDA, LDB
  REAL(8) :: ALPHA
  REAL(8), DIMENSION(:,:) :: A, B

  SUBROUTINE TRSM_64( SIDE, UPLO, [TRANSA], DIAG, [M], [N], ALPHA, A, 
 *       [LDA], B, [LDB])
  CHARACTER(LEN=1) :: SIDE, UPLO, TRANSA, DIAG
  INTEGER(8) :: M, N, LDA, LDB
  REAL(8) :: ALPHA
  REAL(8), DIMENSION(:,:) :: A, B

C INTERFACE

#include <sunperf.h>

void dtrsm(char side, char uplo, char transa, char diag, int m, int n, double alpha, double *a, int lda, double *b, int ldb);

void dtrsm_64(char side, char uplo, char transa, char diag, long m, long n, double alpha, double *a, long lda, double *b, long ldb);

PURPOSE

dtrsm solves one of the matrix equations op( A )*X = alpha*B, or X*op( A ) = alpha*B where alpha is a scalar, X and B are m by n matrices, A is a unit, or non-unit, upper or lower triangular matrix and op( A ) is one of

   op( A ) = A   or   op( A ) = A'.

The matrix X is overwritten on B.

ARGUMENTS

• SIDE (input)
  On entry, SIDE specifies whether op( A ) appears on the left or right of X as follows:

  SIDE = 'L' or 'l' op( A )*X = alpha*B.

  SIDE = 'R' or 'r' X*op( A ) = alpha*B.

  Unchanged on exit.

• UPLO (input)
  On entry, UPLO specifies whether the matrix A 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.

• TRANSA (input)
  On entry, TRANSA specifies the form of op( A ) to be used in the matrix multiplication as follows:

  TRANSA = 'N' or 'n' op( A ) = A.

  TRANSA = 'T' or 't' op( A ) = A'.

  TRANSA = 'C' or 'c' op( A ) = A'.

  Unchanged on exit.

• DIAG (input)
  On entry, DIAG specifies whether or not A is unit triangular 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.

• M (input)
  On entry, M specifies the number of rows of B. M > = 0. Unchanged on exit.

• N (input)
  On entry, N specifies the number of columns of B. N > = 0. Unchanged on exit.

• ALPHA (input)
  On entry, ALPHA specifies the scalar alpha. When alpha is zero then A is not referenced and B need not be set before entry. Unchanged on exit.

• A (input)
  when SIDE = 'L' or 'l' and is n when SIDE = 'R' or 'r'.

  Before entry with UPLO = 'U' or 'u', the leading k by k upper triangular part of the array A must contain the upper triangular matrix and the strictly lower triangular part of A is not referenced.

  Before entry with UPLO = 'L' or 'l', the leading k by k 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 one. Unchanged on exit.

• LDA (input)
  On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. When SIDE = 'L' or 'l' then LDA > = max( 1, m ), when SIDE = 'R' or 'r' then LDA > = max( 1, n ). Unchanged on exit.

• B (input/output)
  Before entry, the leading m by n part of the array B must contain the right-hand side matrix B, and on exit is overwritten by the solution matrix X.

• LDB (input)
  On entry, LDB specifies the first dimension of B as declared in the calling (sub) program. LDB > = max( 1, m ). Unchanged on exit.