2. EL 7
  3. lapack
  4. SLARRR(3)

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slarrr.f(3) LAPACK slarrr.f(3)

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 (integerN, real, dimension( * )D, real, dimension( * )E, integerINFO)

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.

Date:

September 2012

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 95 of file slarrr.f.

Author

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Tue Sep 25 2012 Version 3.4.2