redhat man page for dgemv

DGEMV(l)							   BLAS routine 							  DGEMV(l)

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

	   DOUBLE	PRECISION ALPHA, BETA

	   INTEGER	INCX, INCY, LDA, M, N

	   CHARACTER*1	TRANS

	   DOUBLE	PRECISION A( LDA, * ), X( * ), Y( * )

PURPOSE
       DGEMV  performs one of the matrix-vector operations

       where alpha and beta are scalars, x and y are vectors and A is an m by n matrix.

PARAMETERS
       TRANS  - 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'*x + beta*y.

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

	      Unchanged on exit.

       M      - INTEGER.
	      On entry, M specifies the number of rows of the matrix A.  M must be at least zero.  Unchanged on exit.

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

       ALPHA  - DOUBLE PRECISION.
	      On entry, ALPHA specifies the scalar alpha.  Unchanged on exit.

       A      - 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.  Unchanged on exit.

       LDA    - 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 ).
	      Unchanged on exit.

       X      - 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.  Unchanged on exit.

       INCX   - INTEGER.
	      On entry, INCX specifies the increment for the elements of X. INCX must not be zero.  Unchanged on exit.

       BETA   - DOUBLE PRECISION.
	      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      - 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.

       INCY   - INTEGER.
	      On entry, INCY specifies the increment for the elements of Y. INCY must not be zero.  Unchanged on exit.

	      Level 2 Blas routine.

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

BLAS routine							  16 October 1992							  DGEMV(l)