dlaed0 man page on YellowDog

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

DLAED0(l)			       )			     DLAED0(l)

NAME
       DLAED0  -  compute  all eigenvalues and corresponding eigenvectors of a
       symmetric tridiagonal matrix using the divide and conquer method

SYNOPSIS
       SUBROUTINE DLAED0( ICOMPQ, QSIZ, N, D, E, Q, LDQ, QSTORE,  LDQS,	 WORK,
			  IWORK, INFO )

	   INTEGER	  ICOMPQ, INFO, LDQ, LDQS, N, QSIZ

	   INTEGER	  IWORK( * )

	   DOUBLE	  PRECISION D( * ), E( * ), Q( LDQ, * ), QSTORE( LDQS,
			  * ), WORK( * )

PURPOSE
       DLAED0 computes all eigenvalues and  corresponding  eigenvectors	 of  a
       symmetric tridiagonal matrix using the divide and conquer method.

ARGUMENTS
       ICOMPQ  (input) INTEGER
	       = 0:  Compute eigenvalues only.
	       =  1:   Compute eigenvectors of original dense symmetric matrix
	       also.  On entry, Q  contains  the  orthogonal  matrix  used  to
	       reduce  the original matrix to tridiagonal form.	 = 2:  Compute
	       eigenvalues and eigenvectors of tridiagonal matrix.

       QSIZ   (input) INTEGER
	      The dimension of the orthogonal matrix used to reduce  the  full
	      matrix to tridiagonal form.  QSIZ >= N if ICOMPQ = 1.

       N      (input) INTEGER
	      The dimension of the symmetric tridiagonal matrix.  N >= 0.

       D      (input/output) DOUBLE PRECISION array, dimension (N)
	      On entry, the main diagonal of the tridiagonal matrix.  On exit,
	      its eigenvalues.

       E      (input) DOUBLE PRECISION array, dimension (N-1)
	      The off-diagonal elements of the tridiagonal matrix.  On exit, E
	      has been destroyed.

       Q      (input/output) DOUBLE PRECISION array, dimension (LDQ, N)
	      On entry, Q must contain an N-by-N orthogonal matrix.  If ICOMPQ
	      = 0    Q is not referenced.  If ICOMPQ = 1    On entry, Q	 is  a
	      subset  of  the  columns of the orthogonal matrix used to reduce
	      the full matrix to tridiagonal form corresponding to the	subset
	      of  the  full matrix which is being decomposed at this time.  If
	      ICOMPQ = 2    On entry, Q will be the identity matrix.  On exit,
	      Q contains the eigenvectors of the tridiagonal matrix.

       LDQ    (input) INTEGER
	      The  leading  dimension  of  the	array  Q.  If eigenvectors are
	      desired, then  LDQ >= max(1,N).  In any case,  LDQ >= 1.

	      QSTORE (workspace) DOUBLE PRECISION array, dimension  (LDQS,  N)
	      Referenced  only	when  ICOMPQ  = 1.  Used to store parts of the
	      eigenvector matrix when  the  updating  matrix  multiplies  take
	      place.

       LDQS   (input) INTEGER
	      The  leading dimension of the array QSTORE.  If ICOMPQ = 1, then
	      LDQS >= max(1,N).	 In any case,  LDQS >= 1.

       WORK   (workspace) DOUBLE PRECISION array,
	      If ICOMPQ = 0 or 1, the dimension of WORK must be at least  1  +
	      3*N + 2*N*lg N + 2*N**2 ( lg( N ) = smallest integer k such that
	      2^k >= N ) If ICOMPQ = 2, the dimension of WORK must be at least
	      4*N + N**2.

       IWORK  (workspace) INTEGER array,
	      If  ICOMPQ = 0 or 1, the dimension of IWORK must be at least 6 +
	      6*N + 5*N*lg N.  ( lg( N ) = smallest integer k such that 2^k >=
	      N	 )  If ICOMPQ = 2, the dimension of IWORK must be at least 3 +
	      5*N.

       INFO   (output) INTEGER
	      = 0:  successful exit.
	      < 0:  if INFO = -i, the i-th argument had an illegal value.
	      > 0:  The algorithm failed to compute an eigenvalue while	 work‐
	      ing  on  the  submatrix  lying  in  rows	and columns INFO/(N+1)
	      through mod(INFO,N+1).

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

LAPACK version 3.0		 15 June 2000			     DLAED0(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