chpev (l)  Linux Manuals
chpev: computes all the eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix in packed storage
Command to display chpev
manual in Linux: $ man l chpev
NAME
CHPEV  computes 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

= aqNaq: Compute eigenvalues only;
= aqVaq: Compute eigenvalues and eigenvectors.
 UPLO (input) CHARACTER*1

= aqUaq: Upper triangle of A is stored;
= aqLaq: 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 jth column of A
is stored in the array AP as follows:
if UPLO = aqUaq, AP(i + (j1)*j/2) = A(i,j) for 1<=i<=j;
if UPLO = aqLaq, AP(i + (j1)*(2*nj)/2) = A(i,j) for j<=i<=n.
On exit, AP is overwritten by values generated during the
reduction to tridiagonal form. If UPLO = aqUaq, the diagonal
and first superdiagonal of the tridiagonal matrix T overwrite
the corresponding elements of A, and if UPLO = aqLaq, 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 = aqVaq, then if INFO = 0, Z contains the orthonormal
eigenvectors of the matrix A, with the ith column of Z
holding the eigenvector associated with W(i).
If JOBZ = aqNaq, then Z is not referenced.
 LDZ (input) INTEGER

The leading dimension of the array Z. LDZ >= 1, and if
JOBZ = aqVaq, LDZ >= max(1,N).
 WORK (workspace) COMPLEX array, dimension (max(1, 2*N1))

 RWORK (workspace) REAL array, dimension (max(1, 3*N2))

 INFO (output) INTEGER

= 0: successful exit.
< 0: if INFO = i, the ith argument had an illegal value.
> 0: if INFO = i, the algorithm failed to converge; i
offdiagonal elements of an intermediate tridiagonal
form did not converge to zero.
Pages related to chpev
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 chpevx (l)  computes selected eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix A in packed storage
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