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dlacn2.f(3)				      LAPACK				      dlacn2.f(3)

NAME
       dlacn2.f -

SYNOPSIS
   Functions/Subroutines
       subroutine dlacn2 (N, V, X, ISGN, EST, KASE, ISAVE)
	   DLACN2 estimates the 1-norm of a square matrix, using reverse communication for
	   evaluating matrix-vector products.

Function/Subroutine Documentation
   subroutine dlacn2 (integerN, double precision, dimension( * )V, double precision, dimension( *
       )X, integer, dimension( * )ISGN, double precisionEST, integerKASE, integer, dimension( 3
       )ISAVE)
       DLACN2 estimates the 1-norm of a square matrix, using reverse communication for evaluating
       matrix-vector products.

       Purpose:

	    DLACN2 estimates the 1-norm of a square, real matrix A.
	    Reverse communication is used for evaluating matrix-vector products.

       Parameters:
	   N

		     N is INTEGER
		    The order of the matrix.  N >= 1.

	   V

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

	   X

		     X is DOUBLE PRECISION array, dimension (N)
		    On an intermediate return, X should be overwritten by
			  A * X,   if KASE=1,
			  A**T * X,  if KASE=2,
		    and DLACN2 must be re-called with all the other parameters
		    unchanged.

	   ISGN

		     ISGN is INTEGER array, dimension (N)

	   EST

		     EST is DOUBLE PRECISION
		    On entry with KASE = 1 or 2 and ISAVE(1) = 3, EST should be
		    unchanged from the previous call to DLACN2.
		    On exit, EST is an estimate (a lower bound) for norm(A).

	   KASE

		     KASE is INTEGER
		    On the initial call to DLACN2, 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**T * X.
		    On the final return from DLACN2, KASE will again be 0.

	   ISAVE

		     ISAVE is INTEGER array, dimension (3)
		    ISAVE is used to save variables between calls to DLACN2

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   September 2012

       Further Details:

	     Originally named SONEST, dated March 16, 1988.

	     This is a thread safe version of DLACON, which uses the array ISAVE
	     in place of a SAVE statement, as follows:

		DLACON	   DLACN2
		 JUMP	  ISAVE(1)
		 J	  ISAVE(2)
		 ITER	  ISAVE(3)

       Contributors:
	   Nick Higham, University of Manchester

       References:
	   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.

       Definition at line 137 of file dlacn2.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.2				 Tue Sep 25 2012			      dlacn2.f(3)
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