dlarrr (l) - Linux Man Pages

dlarrr: tests to decide whether the symmetric tridiagonal matrix T warrants expensive computations which guarantee high relative accuracy in the eigenvalues

NAME

DLARRR - tests to decide whether the symmetric tridiagonal matrix T warrants expensive computations which guarantee high relative accuracy in the eigenvalues

SYNOPSIS

SUBROUTINE DLARRR(
N, D, E, INFO )

    
INTEGER N, INFO

    
DOUBLE PRECISION D( * ), E( * )

PURPOSE

Perform tests to decide whether the symmetric tridiagonal matrix T warrants expensive computations which guarantee high relative accuracy in the eigenvalues.

ARGUMENTS

N (input) INTEGER
The order of the matrix. N > 0.
D (input) DOUBLE PRECISION array, dimension (N)
The N diagonal elements of the tridiagonal matrix T.
E (input/output) 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 (output) INTEGER
INFO = 0(default) : the matrix warrants computations preserving relative accuracy. INFO = 1 : the matrix warrants computations guaranteeing only absolute accuracy.

FURTHER DETAILS

Based on contributions by

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