[ новости /+++ | форум | теги | ]

NAME
     slaed0 - compute all eigenvalues and corresponding eigenvec-
     tors  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( *
               )



     #include <sunperf.h>

     void slaed0(int icompq, int qsiz, int n, float *d, float *e,
               float  *q,  int  ldq, float *qstore, int ldqs, int
               *info) ;

PURPOSE
     SLAED0 computes all eigenvalues and corresponding  eigenvec-
     tors  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  sym-
               metric  matrix  also.   On  entry,  Q contains the
               orthogonal matrix  used  to  reduce  the  original
               matrix  to tridiagonal form.  = 2:  Compute eigen-
               values 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) 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  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  eigen-
               vectors  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,
               dimension (1 + 3*N + 2*N*lg N + 2*N**2) ( lg( N  )
               = smallest integer k such that 2^k >= N )

     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 2 + 5*N.

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

Партнёры:

Хостинг: