redhat man page for dlacon

DLACON(l)								 )								 DLACON(l)

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.

LAPACK version 3.0						   15 June 2000 							 DLACON(l)