dlarrr-f(3)

dlarrr.f –

Synopsis

Functions/Subroutines

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.

Function/Subroutine Documentation

subroutine dlarrr (integerN, double precision, dimension( * )D, double precision, dimension( * )E, integerINFO)

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:

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 dlarrr.f.

Author

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