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 y := alpha*A*x
+ beta*y, 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 tri
angular part of A is not referenced. Unchanged on
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 ele
ments 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 vec
tor y. On exit, Y is overwritten by the updated
vector y.
INCY - INTEGER
On entry, INCY specifies the increment for the ele
ments of Y. INCY must not be zero. Unchanged on
exit.
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