Man page or keyword search:   man All Sections 1 - General Commands 2 - System Calls 3 - Subroutines, Functions 4 - Special Files 5 - File Formats 6 - Games and Screensavers 7 - Macros and Conventions 8 - Maintenence Commands 9 - Kernel Interface New Commands Server 4.4BSD AIX Alpinelinux Archlinux Aros BSDOS BSDi Bifrost CentOS Cygwin Darwin Debian DigitalUNIX DragonFly ElementaryOS Fedora FreeBSD Gentoo GhostBSD HP-UX Haiku Hurd IRIX Inferno JazzOS Kali Knoppix LinuxMint MacOSX Mageia Mandriva Manjaro Minix MirBSD NeXTSTEP NetBSD OPENSTEP OSF1 OpenBSD OpenDarwin OpenIndiana OpenMandriva OpenServer OpenSuSE OpenVMS Oracle PC-BSD Peanut Pidora Plan9 QNX Raspbian RedHat Scientific Slackware SmartOS Solaris SuSE SunOS Syllable Tru64 UNIXv7 Ubuntu Ultrix UnixWare Xenix YellowDog aLinux   31559 pages apropos Keyword Search (all sections) Output format html ascii pdf view pdf save postscript

DLACON(3F)							    DLACON(3F)

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.

									Page 1

Vote for polarhome