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sla_porcond.f(3) LAPACK sla_porcond.f(3)

NAME

sla_porcond.f -

SYNOPSIS

Functions/Subroutines


REAL function sla_porcond (UPLO, N, A, LDA, AF, LDAF, CMODE, C, INFO, WORK, IWORK)
SLA_PORCOND estimates the Skeel condition number for a symmetric positive-definite matrix.

Function/Subroutine Documentation

REAL function sla_porcond (characterUPLO, integerN, real, dimension( lda, * )A, integerLDA, real, dimension( ldaf, * )AF, integerLDAF, integerCMODE, real, dimension( * )C, integerINFO, real, dimension( * )WORK, integer, dimension( * )IWORK)

SLA_PORCOND estimates the Skeel condition number for a symmetric positive-definite matrix.

Purpose:


SLA_PORCOND 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 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 triangular factor U or L from the Cholesky factorization
A = U**T*U or A = L*L**T, as computed by SPOTRF.

LDAF


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

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 REAL 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 REAL 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 140 of file sla_porcond.f.

Author

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Tue Sep 25 2012 Version 3.4.2