dgemv.f man page

dgemv.f —

Synopsis

Functions/Subroutines

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

Function/Subroutine Documentation

subroutine dgemv (characterTRANS, integerM, integerN, double precisionALPHA, double precision, dimension(lda,*)A, integerLDA, double precision, dimension(*)X, integerINCX, double precisionBETA, double precision, dimension(*)Y, integerINCY)

DGEMV Purpose:

DGEMV  performs one of the matrix-vector operations

   y := alpha*A*x + beta*y,   or   y := alpha*A**T*x + beta*y,

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

Parameters:

TRANS

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.

M

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

N

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

ALPHA

ALPHA is DOUBLE PRECISION.
 On entry, ALPHA specifies the scalar alpha.

A

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.

LDA

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 ).

X

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.

INCX

INCX is INTEGER
 On entry, INCX specifies the increment for the elements of
 X. INCX must not be zero.

BETA

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.

Y

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.

INCY

INCY is INTEGER
 On entry, INCY specifies the increment for the elements of
 Y. INCY must not be zero.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Further Details:

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.

Definition at line 157 of file dgemv.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

dgemv(3) is an alias of dgemv.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK