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

NAME

dgemv - perform one of the matrix-vector operations y := alpha*A*x + beta*y or y := alpha*A'*x + beta*y

SYNOPSIS

  SUBROUTINE DGEMV( TRANSA, M, N, ALPHA, A, LDA, X, INCX, BETA, Y, 
 *      INCY)
  CHARACTER * 1 TRANSA
  INTEGER M, N, LDA, INCX, INCY
  DOUBLE PRECISION ALPHA, BETA
  DOUBLE PRECISION A(LDA,*), X(*), Y(*)

  SUBROUTINE DGEMV_64( TRANSA, M, N, ALPHA, A, LDA, X, INCX, BETA, Y, 
 *      INCY)
  CHARACTER * 1 TRANSA
  INTEGER*8 M, N, LDA, INCX, INCY
  DOUBLE PRECISION ALPHA, BETA
  DOUBLE PRECISION A(LDA,*), X(*), Y(*)

F95 INTERFACE

  SUBROUTINE GEMV( [TRANSA], [M], [N], ALPHA, A, [LDA], X, [INCX], 
 *       BETA, Y, [INCY])
  CHARACTER(LEN=1) :: TRANSA
  INTEGER :: M, N, LDA, INCX, INCY
  REAL(8) :: ALPHA, BETA
  REAL(8), DIMENSION(:) :: X, Y
  REAL(8), DIMENSION(:,:) :: A

  SUBROUTINE GEMV_64( [TRANSA], [M], [N], ALPHA, A, [LDA], X, [INCX], 
 *       BETA, Y, [INCY])
  CHARACTER(LEN=1) :: TRANSA
  INTEGER(8) :: M, N, LDA, INCX, INCY
  REAL(8) :: ALPHA, BETA
  REAL(8), DIMENSION(:) :: X, Y
  REAL(8), DIMENSION(:,:) :: A

C INTERFACE

#include <sunperf.h>

void dgemv(char transa, int m, int n, double alpha, double *a, int lda, double *x, int incx, double beta, double *y, int incy);

void dgemv_64(char transa, long m, long n, double alpha, double *a, long lda, double *x, long incx, double beta, double *y, long incy);

PURPOSE

dgemv performs one of the matrix-vector operations y := alpha*A*x + beta*y, or y := alpha*A'*x + beta*y, where alpha and beta are scalars, x and y are vectors and A is an m by n matrix.

ARGUMENTS

• TRANSA (input)
  On entry, TRANSA specifies the operation to be performed as follows:

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

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

  TRANSA = 'C' or 'c' y : = alpha*A'*x + beta*y.

  Unchanged on exit.

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

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

• ALPHA (input)
  On entry, ALPHA specifies the scalar alpha. Unchanged on exit.

• A (input)
  Before entry, the leading m by n part of the array A must contain the matrix of coefficients. Unchanged on exit.

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

• X (input)
  ( 1 + ( n - 1 )*abs( INCX ) ) when TRANSA = 'N' or 'n' and at least ( 1 + ( m - 1 )*abs( INCX ) ) otherwise. Before entry, the incremented array X must contain the vector x. Unchanged on exit.

• INCX (input)
  On entry, INCX specifies the increment for the elements of X. INCX < > 0. Unchanged on exit.

• BETA (input)
  On entry, BETA specifies the scalar beta. When BETA is supplied as zero then Y need not be set on input. Unchanged on exit.

• Y (input/output)
  ( 1 + ( m - 1 )*abs( INCY ) ) when TRANSA = '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.

• INCY (input)
  On entry, INCY specifies the increment for the elements of Y. INCY < > 0. Unchanged on exit.