man zsyr (Fonctions bibliothèques) - perform the symmetric rank 1 operation A := alpha*x*( x' ) + A,

NAME

ZSYR - perform the symmetric rank 1 operation A := alpha*x*( x' ) + A,

SYNOPSIS

SUBROUTINE ZSYR(
UPLO, N, ALPHA, X, INCX, A, LDA )
CHARACTER UPLO
INTEGER INCX, LDA, N
COMPLEX*16 ALPHA
COMPLEX*16 A( LDA, * ), X( * )

PURPOSE

ZSYR performs the symmetric rank 1 operation A := alpha*x*( x' ) + A, where alpha is a complex scalar, x is an n element vector 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*16
On entry, ALPHA specifies the scalar alpha. Unchanged on exit.
X - COMPLEX*16 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.
A - COMPLEX*16 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. 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 symmetric 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.
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.