PDL::Opt::Simplex man page on aLinux

Man page or keyword search:  
man Server   7435 pages
apropos Keyword Search (all sections)
Output format
aLinux logo
[printable version]

Simplex(3)	      User Contributed Perl Documentation	    Simplex(3)

NAME
       PDL::Opt::Simplex -- Simplex optimization routines

SYNOPSIS
	use PDL::Opt::Simplex;

	($optimum,$ssize) = simplex($init,$initsize,$minsize,
			$maxiter,
			sub {evaluate_func_at($_[0])},
			sub {display_simplex($_[0])}
			);

DESCRIPTION
       This package implements the commonly used simplex optimization
       algorithm. The basic idea of the algorithm is to move a "simplex" of
       N+1 points in the N-dimensional search space according to certain
       rules. The main benefit of the algorithm is that you do not need to
       calculate the derivatives of your function.

       $init is a 1D vector holding the initial values of the N fitted
       parameters, $optimum is a vector holding the final solution.

       $initsize is the size of $init (more...)

       $minsize is some sort of convergence criterion (more...)	 - e.g.
       $minsize = 1e-6

       The sub is assumed to understand more than 1 dimensions and threading.
       Its signature is 'inp(nparams); [ret]out()'. An example would be

	       sub evaluate_func_at {
		       my($xv) = @_;
		       my $x1 = $xv->slice("(0)");
		       my $x2 = $xv->slice("(1)");
		       return $x1**4 + ($x2-5)**4 + $x1*$x2;
	       }

       Here $xv is a vector holding the current values of the parameters being
       fitted which are then sliced out explicitly as $x1 and $x2.

       $ssize gives a very very approximate estimate of how close we might be
       - it might be miles wrong. It is the euclidean distance between the
       best and the worst vertices. If it is not very small, the algorithm has
       not converged.

FUNCTIONS
       simplex

       Simplex optimization routine

	($optimum,$ssize) = simplex($init,$initsize,$minsize,
			$maxiter,
			sub {evaluate_func_at($_[0])},
			sub {display_simplex($_[0])}
			);

       See module "PDL::Opt::Simplex" for more information.

CAVEATS
       Do not use the simplex method if your function has local minima.	 It
       will not work. Use genetic algorithms or simulated annealing or
       conjugate gradient or momentum gradient descent.

       They will not really work either but they are not guaranteed not to
       work ;) (if you have infinite time, simulated annealing is guaranteed
       to work but only after it has visited every point in your space).

SEE ALSO
       Ron Shaffer's chemometrics web page and references therein:
       "http://chem1.nrl.navy.mil/~shaffer/chemoweb.html".

       Numerical Recipes (bla bla bla XXX ref).

       The demonstration (Examples/Simplex/tsimp.pl and tsimp2.pl).

AUTHOR
       Copyright(C) 1997 Tuomas J. Lukka.  All rights reserved. There is no
       warranty. You are allowed to redistribute this software / documentation
       under certain conditions. For details, see the file COPYING in the PDL
       distribution. If this file is separated from the PDL distribution, the
       copyright notice should be included in the file.

perl v5.10.0			  2004-12-04			    Simplex(3)
[top]

List of man pages available for aLinux

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net