NAME¶

ZSYR - performs 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 where alpha is a complex scalar, x is an n element vector and A is an n by n symmetric matrix.

ARGUMENTS¶

UPLO (input) 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 (input) INTEGER

On entry, N specifies the order of the matrix A. N must be at least zero. Unchanged on exit.

ALPHA (input) COMPLEX*16

On entry, ALPHA specifies the scalar alpha. Unchanged on exit.

X (input) 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 (input) INTEGER

On entry, INCX specifies the increment for the elements of X. INCX must not be zero. Unchanged on exit.

A (input/output) 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 (input) 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.