Technical Reference: Base Operating System and Extensions, Volume 2

CHER or ZHER Subroutine

Purpose

Performs the Hermitian rank 1 operation.

Library

BLAS Library (libblas.a)

FORTRAN Syntax

SUBROUTINE CHER(UPLO, N, ALPHA, X, INCX, A, LDA) REAL ALPHA INTEGER INCX, LDA, N CHARACTER*1 UPLO COMPLEX A(LDA,*), X(*)

SUBROUTINE ZHER(UPLO, N, ALPHA,
X, INCX, A, LDA)
DOUBLE PRECISION ALPHA
INTEGER INCX,LDA,N
CHARACTER*1 UPLO
COMPLEX*16 A(LDA,*), X(*)

Description

The CHER or ZHER subroutine performs the Hermitian rank 1 operation:

A := alpha * x * conjg( x' ) + A

where alpha is a real scalar, x is an N element vector and A is an N by N Hermitian matrix.

Parameters

UPLO	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	On entry, N specifies the order of the matrix A; N must be at least 0; unchanged on exit.
ALPHA	On entry, ALPHA specifies the scalar alpha; unchanged on exit.
X	A vector of dimension at least (1 + (N-1) * abs(INCX) ); on entry, the incremented array X must contain the N element vector x; unchanged on exit.
INCX	On entry, INCX specifies the increment for the elements of X; INCX must not be 0; unchanged on exit.
A	An array of dimension ( LDA, N ); on 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. On 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. The imaginary parts of the diagonal elements need not be set, they are assumed to be 0, and on exit they are set to 0.
LDA	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.