Man page - larrr(3)

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Manual

larrr

NAME
SYNOPSIS
Functions
Detailed Description
Function Documentation
subroutine dlarrr (integer n, double precision, dimension( * ) d, doubleprecision, dimension( * ) e, integer info)
subroutine slarrr (integer n, real, dimension( * ) d, real, dimension( * )e, integer info)
Author

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, doubleprecision, 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

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

Author

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