2. EL 9
  3. blas
  4. dgemv.f(3)

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dgemv.f(3) LAPACK dgemv.f(3)

NAME

dgemv.f

SYNOPSIS

Functions/Subroutines


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

Function/Subroutine Documentation

subroutine dgemv (character TRANS, integer M, integer N, double precision ALPHA, double precision, dimension(lda,*) A, integer LDA, double precision, dimension(*) X, integer INCX, double precision BETA, double precision, dimension(*) Y, integer INCY)

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, 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, 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, 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:

December 2016

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 158 of file dgemv.f.

Author

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