sstev.f (3) - Linux Man Pages

NAME

sstev.f -

SYNOPSIS


Functions/Subroutines


subroutine sstev (JOBZ, N, D, E, Z, LDZ, WORK, INFO)
SSTEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for OTHER matrices

Function/Subroutine Documentation

subroutine sstev (characterJOBZ, integerN, real, dimension( * )D, real, dimension( * )E, real, dimension( ldz, * )Z, integerLDZ, real, dimension( * )WORK, integerINFO)

SSTEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for OTHER matrices

Purpose:

 SSTEV computes all eigenvalues and, optionally, eigenvectors of a
 real symmetric tridiagonal matrix A.


 

Parameters:

JOBZ

          JOBZ is CHARACTER*1
          = 'N':  Compute eigenvalues only;
          = 'V':  Compute eigenvalues and eigenvectors.


N

          N is INTEGER
          The order of the matrix.  N >= 0.


D

          D is REAL array, dimension (N)
          On entry, the n diagonal elements of the tridiagonal matrix
          A.
          On exit, if INFO = 0, the eigenvalues in ascending order.


E

          E is REAL array, dimension (N-1)
          On entry, the (n-1) subdiagonal elements of the tridiagonal
          matrix A, stored in elements 1 to N-1 of E.
          On exit, the contents of E are destroyed.


Z

          Z is REAL array, dimension (LDZ, N)
          If JOBZ = 'V', then if INFO = 0, Z contains the orthonormal
          eigenvectors of the matrix A, with the i-th column of Z
          holding the eigenvector associated with D(i).
          If JOBZ = 'N', then Z is not referenced.


LDZ

          LDZ is INTEGER
          The leading dimension of the array Z.  LDZ >= 1, and if
          JOBZ = 'V', LDZ >= max(1,N).


WORK

          WORK is REAL array, dimension (max(1,2*N-2))
          If JOBZ = 'N', WORK is not referenced.


INFO

          INFO is 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 E did not converge to zero.


 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 117 of file sstev.f.

Author

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