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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
	dlacon(l)

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DLACON

NAME
SYNOPSIS
PURPOSE
ARGUMENTS
FURTHER DETAILS

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NAME

DLACON - estimate the 1-norm of a square, real matrix A

SYNOPSIS

	SUBROUTINE DLACON(		N, V, X, ISGN, EST, KASE )
	INTEGER		KASE, N
	DOUBLE		PRECISION EST
	INTEGER		ISGN( * )
	DOUBLE		PRECISION V( * ), X( * )

PURPOSE

DLACON estimates the 1-norm of a square, real matrix A. Reverse communication is used for evaluating matrix-vector products.

ARGUMENTS

N (input) INTEGER

The order of the matrix. N >= 1.

V (workspace) DOUBLE PRECISION array, dimension (N)

On the final return, V = A*W, where EST = norm(V)/norm(W) (W is not returned).

X (input/output) DOUBLE PRECISION array, dimension (N)

On an intermediate return, X should be overwritten by A * X, if KASE=1, A’ * X, if KASE=2, and DLACON must be re-called with all the other parameters unchanged.

ISGN (workspace) INTEGER array, dimension (N)
EST (output) DOUBLE PRECISION

An estimate (a lower bound) for norm(A).

KASE (input/output) INTEGER

On the initial call to DLACON, KASE should be 0. On an intermediate return, KASE will be 1 or 2, indicating whether X should be overwritten by A * X or A’ * X. On the final return from DLACON, KASE will again be 0.

FURTHER DETAILS

Contributed by Nick Higham, University of Manchester.
Originally named SONEST, dated March 16, 1988.

Reference: N.J. Higham, "FORTRAN codes for estimating the one-norm of a real or complex matrix, with applications to condition estimation", ACM Trans. Math. Soft., vol. 14, no. 4, pp. 381-396, December 1988.

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dlacon(l)