cheevd man page on YellowDog

Man page or keyword search:  
man Server   18644 pages
apropos Keyword Search (all sections)
Output format
YellowDog logo
[printable version]

CHEEVD(l)			       )			     CHEEVD(l)

NAME
       CHEEVD  -  compute  all	eigenvalues and, optionally, eigenvectors of a
       complex Hermitian matrix A

SYNOPSIS
       SUBROUTINE CHEEVD( JOBZ, UPLO,  N,  A,  LDA,  W,	 WORK,	LWORK,	RWORK,
			  LRWORK, IWORK, LIWORK, INFO )

	   CHARACTER	  JOBZ, UPLO

	   INTEGER	  INFO, LDA, LIWORK, LRWORK, LWORK, N

	   INTEGER	  IWORK( * )

	   REAL		  RWORK( * ), W( * )

	   COMPLEX	  A( LDA, * ), WORK( * )

PURPOSE
       CHEEVD computes all eigenvalues and, optionally, eigenvectors of a com‐
       plex Hermitian matrix A. If eigenvectors are desired, it uses a	divide
       and conquer algorithm.

       The  divide  and	 conquer  algorithm  makes very mild assumptions about
       floating point arithmetic. It will work on machines with a guard	 digit
       in add/subtract, or on those binary machines without guard digits which
       subtract like the Cray X-MP, Cray Y-MP, Cray C-90, or Cray-2. It	 could
       conceivably  fail on hexadecimal or decimal machines without guard dig‐
       its, but we know of none.

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.

       A       (input/output) COMPLEX array, dimension (LDA, N)
	       On entry, the Hermitian matrix A.  If UPLO = 'U',  the  leading
	       N-by-N upper triangular part of A contains the upper triangular
	       part of the matrix A.  If UPLO = 'L', the leading N-by-N	 lower
	       triangular  part of A contains the lower triangular part of the
	       matrix A.  On exit, if JOBZ = 'V', then if INFO = 0, A contains
	       the  orthonormal	 eigenvectors of the matrix A.	If JOBZ = 'N',
	       then on exit the lower triangle (if UPLO='L') or the upper tri‐
	       angle (if UPLO='U') of A, including the diagonal, is destroyed.

       LDA     (input) INTEGER
	       The leading dimension of the array A.  LDA >= max(1,N).

       W       (output) REAL array, dimension (N)
	       If INFO = 0, the eigenvalues in ascending order.

       WORK    (workspace/output) COMPLEX array, dimension (LWORK)
	       On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

       LWORK   (input) INTEGER
	       The  length of the array WORK.  If N <= 1,		 LWORK
	       must be at least 1.  If JOBZ  = 'N' and N > 1, LWORK must be at
	       least  N + 1.  If JOBZ  = 'V' and N > 1, LWORK must be at least
	       2*N + N**2.

	       If LWORK = -1, then a workspace query is assumed;  the  routine
	       only  calculates	 the  optimal  size of the WORK array, returns
	       this value as the first entry of the WORK array, and  no	 error
	       message related to LWORK is issued by XERBLA.

       RWORK   (workspace/output) REAL array,
	       dimension  (LRWORK)  On exit, if INFO = 0, RWORK(1) returns the
	       optimal LRWORK.

       LRWORK  (input) INTEGER
	       The   dimension	 of   the   array   RWORK.    If   N   <=   1,
	       LRWORK  must  be	 at least 1.  If JOBZ  = 'N' and N > 1, LRWORK
	       must be at least N.  If JOBZ  = 'V' and N > 1, LRWORK  must  be
	       at least 1 + 5*N + 2*N**2.

	       If  LRWORK = -1, then a workspace query is assumed; the routine
	       only calculates the optimal size of the	RWORK  array,  returns
	       this  value as the first entry of the RWORK array, and no error
	       message related to LRWORK is issued by XERBLA.

       IWORK   (workspace/output) INTEGER array, dimension (LIWORK)
	       On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK.

       LIWORK  (input) INTEGER
	       The   dimension	 of   the   array   IWORK.    If   N   <=   1,
	       LIWORK  must  be	 at least 1.  If JOBZ  = 'N' and N > 1, LIWORK
	       must be at least 1.  If JOBZ  = 'V' and N > 1, LIWORK  must  be
	       at least 3 + 5*N.

	       If  LIWORK = -1, then a workspace query is assumed; the routine
	       only calculates the optimal size of the	IWORK  array,  returns
	       this  value as the first entry of the IWORK array, and no error
	       message related to LIWORK is issued by XERBLA.

       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.

FURTHER DETAILS
       Based on contributions by
	  Jeff Rutter, Computer Science Division, University of California
	  at Berkeley, USA

LAPACK version 3.0		 15 June 2000			     CHEEVD(l)
[top]

List of man pages available for YellowDog

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net