?larrr

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

Syntax

call slarrr( n, d, e, info )

call dlarrr( n, d, e, info )

Include Files

The FORTRAN 77 interfaces are specified in the mkl_lapack.fi include file (to be used in Fortran programs) and in the mkl_lapack.h include file (to be used in C programs).

Description

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

Input Parameters

n

INTEGER. The order of the matrix T. (n > 0).

d

REAL for slarrr

DOUBLE PRECISION for dlarrr

Array, DIMENSION (n).

Contains n diagonal elements of the matrix T.

e

REAL for slarrr

DOUBLE PRECISION for dlarrr

Array, DIMENSION (n).

The first (n-1) entries contain sub-diagonal elements of the tridiagonal matrix T; e(n) is set to 0.

Output Parameters

info

INTEGER.

= 0: the matrix warrants computations preserving relative accuracy (default value).

= -1: the matrix warrants computations guaranteeing only absolute accuracy.