C Library Functions - dtrmm (3)

NAME

dtrmm(3f) - [BLAS:DOUBLE_BLAS_LEVEL3]

Synopsis
Definition
Options
B
Authors
Further Details
See Also

SYNOPSIS

subroutine dtrmm(side,uplo,transa,diag,m,n,alpha,a,lda,b,ldb)

      .. Scalar Arguments ..
      double precision,intent(in)    :: alpha
      integer,intent(in)             :: lda,ldb,m,n
      character,intent(in)           :: diag,side,transa,uplo
      ..
      .. Array Arguments ..
      double precision,intent(in)    :: a(lda,*)
      double precision,intent(inout) :: b(ldb,*)
      ..

DEFINITION

DTRMM performs one of the matrix-matrix operations
    B := alpha*op( A )*B,   or   B := alpha*B*op( A ),
where alpha is a scalar, B is an m by n matrix, 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**T.

OPTIONS

SIDE

SIDE is CHARACTER*1 On entry, SIDE specifies whether op( A ) multiplies B from the left or right as follows:
              SIDE = ’L’ or ’l’   B := alpha*op( A )*B.

              SIDE = ’R’ or ’r’   B := alpha*B*op( A ).

UPLO

UPLO is 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.

TRANSA

TRANSA is 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**T.

              TRANSA = ’C’ or ’c’   op( A ) = A**T.

DIAG

DIAG is 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.

M

M is INTEGER On entry, M specifies the number of rows of B. M must be at least zero.

N

N is INTEGER On entry, N specifies the number of columns of B. N must be at least zero.

ALPHA

ALPHA is 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.

A

A is DOUBLE PRECISION array, 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 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 unity.

LDA

LDA is 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 ).

B

B is DOUBLE PRECISION array, dimension ( LDB, N ) Before entry, the leading m by n part of the array B must contain the matrix B, and on exit is overwritten by the transformed matrix.

LDB

LDB is 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 ).

AUTHORS

o Univ. of Tennessee

o Univ. of California Berkeley

o Univ. of Colorado Denver

o NAG Ltd.
 date:December 2016

FURTHER DETAILS

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.