zsyr(3)

NAME

ZSYR - perform the symmetric rank 1 operation A := al

pha*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 := al

pha*x*( x' ) + A, where alpha is a complex scalar, x is an n ele

ment 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. Un

changed 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. Un

changed on exit.

INCX - INTEGER

On entry, INCX specifies the increment for the ele

ments 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 up

per triangular part of the symmetric matrix and the strictly low

er triangular part of A is not referenced. On exit, the upper

triangular part of the array A is overwritten by the upper trian

gular 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.

LAPACK version 3.0 15 June 2000

ZSYR(3)