redhat man page for dtrsm

DTRSM(l)							   BLAS routine 							  DTRSM(l)

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, * )

PURPOSE
       DTRSM  solves one of the matrix equations

       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.

PARAMETERS
       SIDE   - CHARACTER*1.
	      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   - CHARACTER*1.
	      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 - CHARACTER*1.  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   - CHARACTER*1.
	      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      - INTEGER.
	      On entry, M specifies the number of rows of B. M must be at least zero.  Unchanged on exit.

       N      - INTEGER.
	      On entry, N specifies the number of columns of B.  N must be at least zero.  Unchanged on exit.

       ALPHA  - DOUBLE PRECISION.
	      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      - DOUBLE PRECISION array of DIMENSION ( LDA, k ), where k is m
	      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 refer-
	      enced.  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	unity.	Unchanged on exit.

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

       B      - DOUBLE PRECISION array of DIMENSION ( LDB, n ).
	      Before  entry,  the leading  m by n part of the array  B must contain  the  right-hand  side  matrix  B,	and  on exit  is overwrit-
	      ten by the solution matrix  X.

       LDB    - INTEGER.
	      On entry, LDB specifies the first dimension of B as declared in  the  calling  (sub)  program.   LDB  must  be  at  least max( 1,  m
	      ).  Unchanged on exit.

	      Level 3 Blas routine.

	      --  Written  on  8-February-1989.   Jack Dongarra, Argonne National Laboratory.  Iain Duff, AERE Harwell.  Jeremy Du Croz, Numerical
	      Algorithms Group Ltd.  Sven Hammarling, Numerical Algorithms Group Ltd.

BLAS routine							  16 October 1992							  DTRSM(l)