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AIX Version 4.3 Base Operating System and Extensions Technical Reference, Volume 2
CHEMV or ZHEMV Subroutine
Purpose
Performs matrixvector operations using Hermitian matrices.
Library
BLAS Library (libblas.a)
FORTRAN Syntax
SUBROUTINE CHEMV(UPLO, N, ALPHA, A, LDA,
X, INCX, BETA, Y, INCY)
COMPLEX ALPHA,BETA
INTEGER INCX,INCY,LDA,N
CHARACTER*1 UPLO
COMPLEX A(LDA,*), X(*), Y(*)
SUBROUTINE ZHEMV(UPLO, N, ALPHA, A, LDA,
X, INCX, BETA, Y, INCY)
COMPLEX*16 ALPHA,BETA
INTEGER INCX,INCY,LDA,N
CHARACTER*1 UPLO
COMPLEX*16 A(LDA,*), X(*), Y(*)
Description
The CHEMV or ZHEMV subroutine performs the matrixvector operation:
y := alpha * A * x + beta * y
where alpha and beta are scalars, x and y are N element vectors 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; unchanged on exit. 
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. 
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 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. The imaginary parts of the diagonal elements need not be set and are assumed to be 0; unchanged on exit. 
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. 
X 
A vector of dimension at least (1 + (N1) * 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. 
BETA 
On entry, BETA specifies the scalar beta; when BETA is supplied as 0 then Y need not be set on input; unchanged on exit. 
Y 
A vector of dimension at least (1 + (N1) * abs( INCY ) ); on entry, the incremented array Y must contain the N element vector y; on exit, Y is overwritten by the updated vector y. 
INCY 
On entry, INCY specifies the increment for the elements of Y; INCY must not be 0; unchanged on exit. 
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