dlarrr.f - Man Page

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.

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.

Date:

June 2017

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 96 of file dlarrr.f.