dstev.f(3)

NAME
dstev.f -

SYNOPSIS

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

Function/Subroutine Documentation

  subroutine DSTEV (CHARACTERJOBZ, INTEGERN, DOUBLE PRECISION, dimension( * )D, DOUBLE PRECISION, dimension( * )E, DOUBLE PRECISION, dimension( ldz, * )Z, INTEGERLDZ, DOUBLE PRECISION, dimension( * )WORK, INTEGERINFO)

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

Purpose:

     DSTEV 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 DOUBLE PRECISION 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 DOUBLE PRECISION 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 DOUBLE PRECISION 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 DOUBLE PRECISION 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 dstev.f'.

Author

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