SLACON(3F)							    SLACON(3F)

NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

     SUBROUTINE	SLACON(	N, V, X, ISGN, EST, KASE )

	 INTEGER	KASE, N

	 REAL		EST

	 INTEGER	ISGN( *	)

	 REAL		V( * ),	X( * )

PURPOSE    [Toc]    [Back]

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

ARGUMENTS    [Toc]    [Back]

     N	    (input) INTEGER
	    The	order of the matrix.  N	>= 1.

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

     X	    (input/output) REAL	array, dimension (N)
	    On an intermediate return, X should	be overwritten by A * X,   if
	    KASE=1, A' * X,  if	KASE=2,	and SLACON must	be re-called with all
	    the	other parameters unchanged.

     ISGN   (workspace)	INTEGER	array, dimension (N)

     EST    (output) REAL
	    An estimate	(a lower bound)	for norm(A).

     KASE   (input/output) INTEGER
	    On the initial call	to SLACON, 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 SLACON, 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.
SLACON(3F)							    SLACON(3F)

NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

     SUBROUTINE	SLACON(	N, V, X, ISGN, EST, KASE )

	 INTEGER	KASE, N

	 REAL		EST

	 INTEGER	ISGN( *	)

	 REAL		V( * ),	X( * )

PURPOSE    [Toc]    [Back]

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

ARGUMENTS    [Toc]    [Back]

     N	    (input) INTEGER
	    The	order of the matrix.  N	>= 1.

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

     X	    (input/output) REAL	array, dimension (N)
	    On an intermediate return, X should	be overwritten by A * X,   if
	    KASE=1, A' * X,  if	KASE=2,	and SLACON must	be re-called with all
	    the	other parameters unchanged.

     ISGN   (workspace)	INTEGER	array, dimension (N)

     EST    (output) REAL
	    An estimate	(a lower bound)	for norm(A).

     KASE   (input/output) INTEGER
	    On the initial call	to SLACON, 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 SLACON, 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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