F_CHPR2/F_ZHPR2

 

 

Hermitian rank-2 update

Name

F_CHPR2/F_ZHPR2

 

 

 

 

Hermitian rank-2 update

 

 

 

Purpose

F_xHPR2 performs the Hermitian rank-2 update

 

 

 

A ← αx y∗ +

a

yx∗ + βA with A=A∗

 

where A is an n-by-ncomplex Hermitian matrix stored in packed form, α is a

 

complex scalar,

α

is the complex conjugate of α, x and y are complex n-vectors,

 

and x* and y* are the conjugate transposes of x and y, respectively. This routine

 

returns immediately if n is less than or equal to zero.

 

Refer to “SSPR2/DSPR2/CHPR2/ZHPR2” on page 259 for a description of the

 

equivalent HP MLIB legacy BLAS subprograms and an illustration of the

 

packed storage of symmetric or Hermitian matrices.

Matrix

Because either triangle of A can be obtained from the other, you only need to

Storage

provide one triangle of A, either the upper or the lower triangle. Compared to

 

storing the entire matrix, you save memory by supplying that triangle stored

 

column-by-column in packed form in a 1-dimensional array (refer to the AP

 

matrix).

 

 

 

Usage

VECLIB

 

 

 

 

INTEGER*4

INCX, INCY, LDA, N, UPLO

 

REAL*4

BETA

 

COMPLEX*8

ALPHA, A( LDA, * ), X( * ), Y( * )

 

SUBROUTINE F_CHER2 (UPLO, N, ALPHA, X, INCX, Y, INCY, BETA, AP)

 

INTEGER*4

INCX, INCY, LDA, N, UPLO

 

REAL*8

BETA

 

COMPLEX*16

ALPHA, A( LDA, * ), X( * ), Y( * )

 

SUBROUTINE F_ZHER2 (UPLO, N, ALPHA, X, INCX, Y, INCY, BETA, AP)

 

VECLIB8

 

 

 

 

INTEGER*8

INCX, INCY, LDA, N, UPLO

 

REAL*4

BETA

 

COMPLEX*8

ALPHA, A( LDA, * ), X( * ), Y( * )

 

SUBROUTINE F_CHER2 (UPLO, N, ALPHA, X, INCX, Y, INCY, BETA, AP)

 

INTEGER*8

INCX, INCY, LDA, N, UPLO

 

REAL*8

BETA

 

COMPLEX*16

ALPHA, A( LDA, * ), X( * ), Y( * )

 

SUBROUTINE F_ZHER2 (UPLO, N, ALPHA, X, INCX, Y, INCY, BETA, AP)

352HP MLIB User’s Guide