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JMERELO / Algorithm-Evolutionary-0.82.1 / lib / Algorithm / Evolutionary / Fitness / ZDT1.pm 

            

              
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use strict; # -*- cperl -*-
use warnings;
use lib qw( ../../../../lib );
=head1 NAME
Algorithm::Evolutionary::Fitness::ZDT1 - Zitzler-Deb-Thiele #1 Multiobjective test function
=head1 SYNOPSIS
    my $number_of_bits = 5;
    my $z = Algorithm::Evolutionary::Fitness::ZDT1->new( $number_of_bits);
    my $string = "10101"x30;
    $z->zdt1( $string);
    #Previously created binary chromosome with 5x30 bits
    $z->apply( $chromosome );
=head1 DESCRIPTION
Implementation of the first ZDT test function, found at "Comparison of Multiobjective Evolutionary
Algorithms: Empirical Results" by Zitzler, Deb and Thiele
=head1 METHODS
=cut
package Algorithm::Evolutionary::Fitness::ZDT1;
our $VERSION =   sprintf "%d.%03d", q$Revision: 3.1 $ =~ /(\d+)\.(\d+)/g; 
use Carp qw(croak);
use lib qw(../../.. ../.. ..);
use base qw(Algorithm::Evolutionary::Fitness::String);
use Algorithm::Evolutionary::Utils qw(decode_string);
use constant { M => 30,
               NINE => 9 };
=head2 new
Creates a new instance of the problem, with the said number of bits and peaks
=cut 
sub new {
  my $class = shift;
  my $number_of_bits = shift || croak "Need non-null number of bits\n";
  my $self = { '_number_of_bits'  => $number_of_bits };
  bless $self, $class;
  $self->initialize();
  return $self;
}
=head2 _really_apply
Applies the instantiated problem to a chromosome
=cut
sub _really_apply {
  my $self = shift;
  my $chromosome_string = shift || croak "No chromosome!!!\n";
  return $self->zdt1( $chromosome_string );
}
=head2 zdt1
Computes ZDT1, returning an array hash with the values of f1 and f2.
=cut
sub zdt1 {
    my $self = shift;
    my $string = shift;
    my @vector = decode_string( $string, 
                                $self->{'_number_of_bits'},
                                0, 1 );
    my $g = g( @vector );
    my $h = 1-sqrt($vector[0]/$g);
    return [ $vector[0], $g*$h ];
}
=head2 g
G function in ZDT
=cut
sub g {
  my @x = @_;
  my $sum =0;
  map( $sum += $_, @x[1..$#x] );
  return 1+NINE*$sum/(M-1);
}
=head1 Copyright
   
  This file is released under the GPL. See the LICENSE file included in this distribution,
  or go to http://www.fsf.org/licenses/gpl.txt
  CVS Info: $Date: 2009/07/24 10:25:49 $ 
  $Header: /media/Backup/Repos/opeal/opeal/Algorithm-Evolutionary/lib/Algorithm/Evolutionary/Fitness/ZDT1.pm,v 3.1 2009/07/24 10:25:49 jmerelo Exp $ 
  $Author: jmerelo $ 
  $Revision: 3.1 $
  $Name $
=cut
"What???";