DLA_SYRCOND (3) Linux Manual Page

dla_syrcond.f –

Synopsis

Functions/Subroutines

DOUBLE PRECISION function dla_syrcond (UPLO, N, A, LDA, AF, LDAF, IPIV, CMODE, C, INFO, WORK, IWORK)
DLA_SYRCOND estimates the Skeel condition number for a symmetric indefinite matrix.

Function/Subroutine Documentation

DOUBLE PRECISION function dla_syrcond (characterUPLO, integerN, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( ldaf, * )AF, integerLDAF, integer, dimension( * )IPIV, integerCMODE, double precision, dimension( * )C, integerINFO, double precision, dimension( * )WORK, integer, dimension( * )IWORK)

DLA_SYRCOND estimates the Skeel condition number for a symmetric indefinite matrix.

Purpose:

 DLA_SYRCOND estimates the Skeel condition number of op(A) * op2(C)

 where op2 is determined by CMODE as follows

 CMODE = 1 op2(C) = C

 CMODE = 0 op2(C) = I

 CMODE = -1 op2(C) = inv(C)

 The Skeel condition number cond(A) = norminf( |inv(A)||A| )

 is computed by computing scaling factors R such that

 diag(R)*A*op2(C) is row equilibrated and computing the standard

 infinity-norm condition number.

 

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.

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.

CMODE

 CMODE is INTEGER

 Determines op2(C) in the formula op(A) * op2(C) as follows:

 CMODE = 1 op2(C) = C

 CMODE = 0 op2(C) = I

 CMODE = -1 op2(C) = inv(C)

C

 C is DOUBLE PRECISION array, dimension (N)

 The vector C in the formula op(A) * op2(C).

INFO

 INFO is INTEGER

 = 0: Successful exit.

 i > 0: The ith argument is invalid.

WORK

 WORK is DOUBLE PRECISION array, dimension (3*N).

 Workspace.

IWORK

 IWORK is INTEGER array, dimension (N).

 Workspace.

 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 147 of file dla_syrcond.f.

Author

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