CHEMV - perform the matrix-vector operation y :=
alpha*A*x + beta*y,
SYNOPSIS
SUBROUTINE CHEMV ( UPLO, N, ALPHA, A, LDA, X, INCX, BETA,
Y, INCY )
COMPLEX ALPHA, BETA
INTEGER INCX, INCY, LDA, N
CHARACTER*1 UPLO
COMPLEX A( LDA, * ), X( * ), Y( * )
PURPOSE
CHEMV 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 hermitian matrix.
PARAMETERS
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 of DIMENSION ( LDA, n ).
Before entry with UPLO = 'U' or 'u', the leading n
by n upper triangular part of the array A must con
tain the upper triangular part of the hermitian
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 hermitian matrix and the strictly upper
the imaginary parts of the diagonal elements need
not be set and are assumed to be zero. 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 of dimension at least
( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the
incremented array X must contain the n element vec
tor 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 of 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.
Level 2 Blas routine.
-- 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.
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