larrr(3)

NAME
larrr - larrr: step in stemr, test to do expensive tridiag eig algorithm

SYNOPSIS

  Functions
subroutine dlarrr (n, d, e, info)
DLARRR performs tests to decide whether the symmetric tridiagonal matrix T warrants expensive computations which guarantee high relative accuracy in the eigenvalues.
subroutine slarrr (n, d, e, info)
SLARRR performs tests to decide whether the symmetric tridiagonal matrix T warrants expensive computations which guarantee high relative accuracy in the eigenvalues.

Detailed Description

Function Documentation

  subroutine dlarrr (integer n, double precision, dimension( * ) d, double precision, dimension( * ) e, integer info)

DLARRR performs tests to decide whether the symmetric tridiagonal matrix T warrants expensive computations which guarantee high relative accuracy in the eigenvalues.

Purpose:

     Perform tests to decide whether the symmetric tridiagonal matrix T
     warrants expensive computations which guarantee high relative accuracy
     in the eigenvalues.

Parameters
    N

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

    D

              D is DOUBLE PRECISION array, dimension (N)
              The N diagonal elements of the tridiagonal matrix T.

    E

              E is DOUBLE PRECISION array, dimension (N)
              On entry, the first (N-1) entries contain the subdiagonal
              elements of the tridiagonal matrix T; E(N) is set to ZERO.

    INFO

              INFO is INTEGER
              INFO = 0(default) : the matrix warrants computations preserving
                                  relative accuracy.
              INFO = 1          : the matrix warrants computations guaranteeing
                                  only absolute accuracy.

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Contributors:
    Beresford Parlett, University of California, Berkeley, USA
     Jim Demmel, University of California, Berkeley, USA
     Inderjit Dhillon, University of Texas, Austin, USA
     Osni Marques, LBNL/NERSC, USA
     Christof Voemel, University of California, Berkeley, USA

Definition at line 93 of file dlarrr.f.

  subroutine slarrr (integer n, real, dimension( * ) d, real, dimension( * ) e, integer info)

SLARRR performs tests to decide whether the symmetric tridiagonal matrix T warrants expensive computations which guarantee high relative accuracy in the eigenvalues.

Purpose:

     Perform tests to decide whether the symmetric tridiagonal matrix T
     warrants expensive computations which guarantee high relative accuracy
     in the eigenvalues.

Parameters
    N

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

    D

              D is REAL array, dimension (N)
              The N diagonal elements of the tridiagonal matrix T.

    E

              E is REAL array, dimension (N)
              On entry, the first (N-1) entries contain the subdiagonal
              elements of the tridiagonal matrix T; E(N) is set to ZERO.

    INFO

              INFO is INTEGER
              INFO = 0(default) : the matrix warrants computations preserving
                                  relative accuracy.
              INFO = 1          : the matrix warrants computations guaranteeing
                                  only absolute accuracy.

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Contributors:
    Beresford Parlett, University of California, Berkeley, USA
     Jim Demmel, University of California, Berkeley, USA
     Inderjit Dhillon, University of Texas, Austin, USA
     Osni Marques, LBNL/NERSC, USA
     Christof Voemel, University of California, Berkeley, USA

Definition at line 93 of file slarrr.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.