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Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :

ISBN : 978-2-7460-9712-4
EAN : 9782746097124
(Editions ENI)

GNU/Linux	CentOS 4.8	i386
	chpev(l)

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CHPEV

NAME
SYNOPSIS
PURPOSE
ARGUMENTS

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NAME

CHPEV - compute all the eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix in packed storage

SYNOPSIS

	SUBROUTINE CHPEV(		JOBZ, UPLO, N, AP, W, Z, LDZ, WORK, RWORK, INFO )
	CHARACTER		JOBZ, UPLO
	INTEGER		INFO, LDZ, N
	REAL		RWORK( * ), W( * )
	COMPLEX		AP( * ), WORK( * ), Z( LDZ, * )

PURPOSE

CHPEV computes all the eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix in packed storage.

ARGUMENTS

JOBZ (input) CHARACTER*1

= ’N’: Compute eigenvalues only;
= ’V’: Compute eigenvalues and eigenvectors.

UPLO (input) CHARACTER*1

= ’U’: Upper triangle of A is stored;
= ’L’: Lower triangle of A is stored.

N (input) INTEGER

The order of the matrix A. N >= 0.

AP (input/output) COMPLEX array, dimension (N*(N+1)/2)

On entry, the upper or lower triangle of the Hermitian matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array AP as follows: if UPLO = ’U’, AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = ’L’, AP(i + (j-1)*(2*n-j)/2) = A(i,j) for j<=i<=n.

On exit, AP is overwritten by values generated during the reduction to tridiagonal form. If UPLO = ’U’, the diagonal and first superdiagonal of the tridiagonal matrix T overwrite the corresponding elements of A, and if UPLO = ’L’, the diagonal and first subdiagonal of T overwrite the corresponding elements of A.

W (output) REAL array, dimension (N)

If INFO = 0, the eigenvalues in ascending order.

Z (output) COMPLEX array, dimension (LDZ, N)

If JOBZ = ’V’, then if INFO = 0, Z contains the orthonormal eigenvectors of the matrix A, with the i-th column of Z holding the eigenvector associated with W(i). If JOBZ = ’N’, then Z is not referenced.

LDZ (input) INTEGER

The leading dimension of the array Z. LDZ >= 1, and if JOBZ = ’V’, LDZ >= max(1,N).

WORK (workspace) COMPLEX array, dimension (max(1, 2*N-1))
RWORK (workspace) REAL array, dimension (max(1, 3*N-2))
INFO (output) INTEGER

= 0: successful exit.
< 0: if INFO = -i, the i-th argument had an illegal value.
> 0: if INFO = i, the algorithm failed to converge; i off-diagonal elements of an intermediate tridiagonal form did not converge to zero.

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chpev(l)