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Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :

ISBN : 978-2-7460-9712-4
EAN : 9782746097124
(Editions ENI)

GNU/Linux	CentOS 4.8	i386
	dgecon(l)

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DGECON

NAME
SYNOPSIS
PURPOSE
ARGUMENTS

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NAME

DGECON - estimate the reciprocal of the condition number of a general real matrix A, in either the 1-norm or the infinity-norm, using the LU factorization computed by DGETRF

SYNOPSIS

	SUBROUTINE DGECON(		NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK, INFO )
	CHARACTER		NORM
	INTEGER		INFO, LDA, N
	DOUBLE		PRECISION ANORM, RCOND
	INTEGER		IWORK( * )
	DOUBLE		PRECISION A( LDA, * ), WORK( * )

PURPOSE

DGECON estimates the reciprocal of the condition number of a general real matrix A, in either the 1-norm or the infinity-norm, using the LU factorization computed by DGETRF. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as
RCOND = 1 / ( norm(A) * norm(inv(A)) ).

ARGUMENTS

NORM (input) CHARACTER*1

Specifies whether the 1-norm condition number or the infinity-norm condition number is required:
= ’1’ or ’O’: 1-norm;
= ’I’: Infinity-norm.

N (input) INTEGER

The order of the matrix A. N >= 0.

A (input) DOUBLE PRECISION array, dimension (LDA,N)

The factors L and U from the factorization A = P*L*U as computed by DGETRF.

LDA (input) INTEGER

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

ANORM (input) DOUBLE PRECISION

If NORM = ’1’ or ’O’, the 1-norm of the original matrix A. If NORM = ’I’, the infinity-norm of the original matrix A.

RCOND (output) DOUBLE PRECISION

The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).

WORK (workspace) DOUBLE PRECISION array, dimension (4*N)
IWORK (workspace) INTEGER array, dimension (N)
INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value

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dgecon(l)