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larrr(3) Library Functions Manual larrr(3)

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, double precision, 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

Definition at line 93 of file dlarrr.f.

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

Definition at line 93 of file slarrr.f.

Author

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