NAME
cher2 - perform the hermitian rank 2 operation A :=
alpha*x*conjg( y' ) + conjg( alpha )*y*conjg( x' ) + A
SYNOPSIS
SUBROUTINE CHER2 ( UPLO, N, ALPHA, X, INCX, Y, INCY, A, LDA
)
COMPLEX ALPHA
INTEGER INCX, INCY, LDA, N
CHARACTER*1 UPLO
COMPLEX A( LDA, * ), X( * ), Y( * )
#include <sunperf.h>
void cher2(char uplo, int n, complex *calpha, complex * x,
int incx, complex *cy, int incy, complex *ca, int
lda) ;
PURPOSE
CHER2 performs the hermitian rank 2 operation A :=
alpha*x*conjg( y' ) + conjg( alpha )*y*conjg( x' ) + A where
alpha is a scalar, 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.
X - COMPLEX array of 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.
Y - COMPLEX array of dimension at least
( 1 + ( n - 1 )*abs( INCY ) ). Before entry, the
incremented array Y must contain the n element
vector y. Unchanged on exit.
INCY - INTEGER.
On entry, INCY specifies the increment for the
elements of Y. INCY must not be zero. 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
contain the upper triangular part of the hermitian
matrix and the strictly lower triangular part of A
is not referenced. On exit, the upper triangular
part of the array A is overwritten by the upper
triangular part of the updated matrix. 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 triangular part of A is not
referenced. On exit, the lower triangular part of
the array A is overwritten by the lower triangular
part of the updated matrix. Note that the ima-
ginary parts of the diagonal elements need not be
set, they are assumed to be zero, and on exit they
are set to zero.
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.
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