ESMF_DGEMV Subroutine

subroutine ESMF_DGEMV(TRANS, M, N, ALPHA, A, LDA, X, INCX, BETA, Y, INCY)

\brief \b ESMF_DGEMV \par Purpose:

\verbatim

ESMF_DGEMV performs one of the matrix-vector operations

y := alphaAx + betay, or y := alphaATx + betay,

where alpha and beta are scalars, x and y are vectors and A is an m by n matrix. \endverbatim \param[in] TRANS \verbatim TRANS is CHARACTER*1 On entry, TRANS specifies the operation to be performed as follows:

         TRANS = 'N' or 'n'   y := alpha*A*x + beta*y.

         TRANS = 'T' or 't'   y := alpha*A**T*x + beta*y.

         TRANS = 'C' or 'c'   y := alpha*A**T*x + beta*y.

\endverbatim

\param[in] M \verbatim M is INTEGER On entry, M specifies the number of rows of the matrix A. M must be at least zero. \endverbatim

\param[in] N \verbatim N is INTEGER On entry, N specifies the number of columns of the matrix A. N must be at least zero. \endverbatim

\param[in] ALPHA \verbatim ALPHA is DOUBLE PRECISION. On entry, ALPHA specifies the scalar alpha. \endverbatim

\param[in] A \verbatim A is DOUBLE PRECISION array of DIMENSION ( LDA, n ). Before entry, the leading m by n part of the array A must contain the matrix of coefficients. \endverbatim

\param[in] LDA \verbatim LDA is INTEGER On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. LDA must be at least max( 1, m ). \endverbatim

\param[in] X \verbatim X is DOUBLE PRECISION array of DIMENSION at least ( 1 + ( n - 1 )abs( INCX ) ) when TRANS = ‘N’ or ‘n’ and at least ( 1 + ( m - 1 )abs( INCX ) ) otherwise. Before entry, the incremented array X must contain the vector x. \endverbatim

\param[in] INCX \verbatim INCX is INTEGER On entry, INCX specifies the increment for the elements of X. INCX must not be zero. \endverbatim

\param[in] BETA \verbatim BETA is DOUBLE PRECISION. On entry, BETA specifies the scalar beta. When BETA is supplied as zero then Y need not be set on input. \endverbatim

\param[in,out] Y \verbatim Y is DOUBLE PRECISION array of DIMENSION at least ( 1 + ( m - 1 )abs( INCY ) ) when TRANS = ‘N’ or ‘n’ and at least ( 1 + ( n - 1 )abs( INCY ) ) otherwise. Before entry with BETA non-zero, the incremented array Y must contain the vector y. On exit, Y is overwritten by the updated vector y. \endverbatim

\param[in] INCY \verbatim INCY is INTEGER On entry, INCY specifies the increment for the elements of Y. INCY must not be zero. \endverbatim \author Univ. of Tennessee \author Univ. of California Berkeley \author Univ. of Colorado Denver \author NAG Ltd. \date November 2011 \ingroup double_blas_level2 \par Further Details:

\verbatim

Level 2 Blas routine. The vector and matrix arguments are not referenced when N = 0, or M = 0

– Written on 22-October-1986. Jack Dongarra, Argonne National Lab. Jeremy Du Croz, Nag Central Office. Sven Hammarling, Nag Central Office. Richard Hanson, Sandia National Labs. \endverbatim

Arguments