Home Man
Search
Today's Posts
Register

Linux & Unix Commands - Search Man Pages

RedHat 9 (Linux i386) - man page for slaed0 (redhat section l)

SLAED0(l)					)					SLAED0(l)

NAME
       SLAED0 - compute all eigenvalues and corresponding eigenvectors of a symmetric tridiagonal
       matrix using the divide and conquer method

SYNOPSIS
       SUBROUTINE SLAED0( ICOMPQ, QSIZ, N, D, E, Q, LDQ, QSTORE, LDQS, WORK, IWORK, INFO )

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

	   INTEGER	  IWORK( * )

	   REAL 	  D( * ), E( * ), Q( LDQ, * ), QSTORE( LDQS, * ), WORK( * )

PURPOSE
       SLAED0 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 tridiago-
	      nal form.  QSIZ >= N if ICOMPQ = 1.

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

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

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

       Q      (input/output) REAL 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 orthog-
	      onal 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) REAL 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) REAL 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 working 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 				SLAED0(l)


All times are GMT -4. The time now is 11:27 PM.

Unix & Linux Forums Content Copyrightę1993-2018. All Rights Reserved.
UNIX.COM Login
Username:
Password:  
Show Password