NAME

csymv - perform the matrix-vector operation   y := alpha∗A∗x + beta∗y,

SYNOPSIS

SUBROUTINE CSYMV(
UPLO, N, ALPHA, A, LDA, X, INCX, BETA, Y, INCY )

CHARACTER UPLO

INTEGER INCX, INCY, LDA, N

COMPLEX ALPHA, BETA

COMPLEX A( LDA, ∗ ), X( ∗ ), Y( ∗ )

PURPOSE

CSYMV  performs the matrix-vector  operation
 
where alpha and beta are scalars, x and y are n element vectors and A is an n by n symmetric matrix.
 

ARGUMENTS

UPLO   - CHARACTER∗1
On entry, UPLO specifies whether the upper or lower triangular part of the array A is to be referenced as follows:
 
UPLO = ’U’ or ’u’   Only the upper triangular part of A is to be referenced.
 
UPLO = ’L’ or ’l’   Only the lower triangular part of A is to be referenced.
 
Unchanged on exit.

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

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

A      - COMPLEX array, dimension ( LDA, N )
Before entry, with  UPLO = ’U’ or ’u’, the leading n by n upper triangular part of the array A must contain the upper triangular part of the symmetric matrix and the strictly lower triangular part of A is not referenced. Before entry, with UPLO = ’L’ or ’l’, the leading n by n lower triangular part of the array A must contain the lower triangular part of the symmetric matrix and the strictly upper triangular part of A is not referenced. 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, N ). Unchanged on exit.

X      - COMPLEX array, dimension at least
( 1 + ( N - 1 )∗abs( INCX ) ). Before entry, the incremented array X must contain the N- element 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   - COMPLEX
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      - COMPLEX array, dimension at least
( 1 + ( N - 1 )∗abs( INCY ) ). Before entry, the incremented array Y must contain the n element 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.

SunSoft, Inc.  —  Last change: 27 Jun 1995