slarrr.f

Section: LAPACK (3)
Updated: Tue Nov 14 2017
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NAME

slarrr.f

SYNOPSIS

Functions/Subroutines

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.

Function/Subroutine Documentation

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

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

          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.

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 slarrr.f.

Author

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