ssterf.f

NAME

ssterf.f −

SYNOPSIS

Functions/Subroutines

subroutine ssterf (N, D, E, INFO)
SSTERF

Function/Subroutine Documentation

subroutine ssterf (integerN, real, dimension( * )D, real, dimension( * )E, integerINFO)
SSTERF

Purpose:

SSTERF computes all eigenvalues of a symmetric tridiagonal matrix
using the Pal-Walker-Kahan variant of the QL or QR algorithm.

Parameters:

N

N is INTEGER
The order of the matrix. N >= 0.

D

D is REAL array, dimension (N)
On entry, the n diagonal elements of the tridiagonal matrix.
On exit, if INFO = 0, the eigenvalues in ascending order.

E

E is REAL array, dimension (N-1)
On entry, the (n-1) subdiagonal elements of the tridiagonal
matrix.
On exit, E has been destroyed.

INFO

INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: the algorithm failed to find all of the eigenvalues in
a total of 30*N iterations; if INFO = i, then i
elements of E have not converged to zero.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 87 of file ssterf.f.

Author

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