sla_syrpvgrw.f man page

sla_syrpvgrw.f —

Synopsis

Functions/Subroutines

REAL function sla_syrpvgrw (UPLO, N, INFO, A, LDA, AF, LDAF, IPIV, WORK)
SLA_SYRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.

Function/Subroutine Documentation

REAL function sla_syrpvgrw (character*1UPLO, integerN, integerINFO, real, dimension( lda, * )A, integerLDA, real, dimension( ldaf, * )AF, integerLDAF, integer, dimension( * )IPIV, real, dimension( * )WORK)

SLA_SYRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.

Purpose:

SLA_SYRPVGRW computes the reciprocal pivot growth factor
norm(A)/norm(U). The "max absolute element" norm is used. If this is
much less than 1, the stability of the LU factorization of the
(equilibrated) matrix A could be poor. This also means that the
solution X, estimated condition numbers, and error bounds could be
unreliable.

Parameters:

UPLO

   UPLO is CHARACTER*1
= 'U':  Upper triangle of A is stored;
= 'L':  Lower triangle of A is stored.

N

     N is INTEGER
The number of linear equations, i.e., the order of the
matrix A.  N >= 0.

INFO

     INFO is INTEGER
The value of INFO returned from SSYTRF, .i.e., the pivot in
column INFO is exactly 0.

A

     A is REAL array, dimension (LDA,N)
On entry, the N-by-N matrix A.

LDA

     LDA is INTEGER
The leading dimension of the array A.  LDA >= max(1,N).

AF

     AF is REAL array, dimension (LDAF,N)
The block diagonal matrix D and the multipliers used to
obtain the factor U or L as computed by SSYTRF.

LDAF

     LDAF is INTEGER
The leading dimension of the array AF.  LDAF >= max(1,N).

IPIV

     IPIV is INTEGER array, dimension (N)
Details of the interchanges and the block structure of D
as determined by SSYTRF.

WORK

WORK is REAL array, dimension (2*N)

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 122 of file sla_syrpvgrw.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

sla_syrpvgrw(3) is an alias of sla_syrpvgrw.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK