DLA_SYRPVGRW (3) Linux Manual Page

dla_syrpvgrw.f –

Synopsis

Functions/Subroutines

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

Function/Subroutine Documentation

DOUBLE PRECISION function dla_syrpvgrw (character*1UPLO, integerN, integerINFO, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( ldaf, * )AF, integerLDAF, integer, dimension( * )IPIV, double precision, dimension( * )WORK)

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

Purpose:

 DLA_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 DSYTRF, .i.e., the pivot in

 column INFO is exactly 0.

A

 A is DOUBLE PRECISION 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 DOUBLE PRECISION array, dimension (LDAF,N)

 The block diagonal matrix D and the multipliers used to

 obtain the factor U or L as computed by DSYTRF.

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 DSYTRF.

WORK

 WORK is DOUBLE PRECISION 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 dla_syrpvgrw.f.

Author

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