NAME

Games::Ratings::Chess::DWZ - calculate changes to German ratings (DWZ)

VERSION

This documentation refers to Games::Ratings::Chess::DWZ version 0.0.3

SYNOPSIS

 use Games::Ratings::Chess::DWZ;

 my $player = Games::Ratings::Chess::DWZ->new();
 $player->set_rating(2135);
 $player->set_coefficent(30);
 $player->add_game( {
                      'opponent_rating' => 2114,
                      'result'          => 'win', ## or 'draw' or 'loss'
                    }
                  );

 my $rating_change = $player->get_rating_change();
 my $new_rating = $player->get_new_rating();

DESCRIPTION

This module provides methods to calculate German chess rating (DZW) changes for one player, having played one or more rated games. Gains and losses are calculated according to Wertungsordnung of the German Chess Federation (http://www.schachbund.de/dwz/wo/index.html).

Actually the official rating calculation _does not_ follow the Wertungsordnung exactly(!) For official rating calculations a closed source program (ELOBASE) is used. That program uses tables with three post decimal positions -- in contrast to the tables from appendix 2.1 and 2.2 of the official Wertungsordnung. Therefore my module uses those more detailed tables as well.

INTERFACE

This modules provides the following methods specific to German ratings. Other (more generic) methods for rating calculation are provided by Games::Ratings.

get_rating_change

  my $rating_change = sprintf( "%+.2f", $player->get_rating_change() );

Calculate rating changes for all stored games and return sum of those changes.

get_new_rating

  my $new_rating = $player->get_new_rating();

Calculate new rating after the given games.

get_points_expected

  my $points_expected = $player->get_points_expected();

Calculate expected points (Punkterwartung) according to rating differences between own rating and opponents ratings. This method uses the detailed probability tables mentioned above (see DESCRIPTION).

get_performance

  my $performance = $player->get_performance();

Calculate performance (Turnierleistung). This method uses the detailed probability tables mentioned above (see DESCRIPTION).

CONFIGURATION AND ENVIRONMENT

Games::Ratings requires no configuration files or environment variables.

DEPENDENCIES

This module relies on Games::Ratings which provides some generic methods, e.g. * new() * get_rating() * set_rating() * get_coefficient() * set_coefficient() * add_game() * remove_all_games() * DESTROY()

DIAGNOSTICS

At the moment, there are no error or warning messages that the module can generate.

Error message here, perhaps with %s placeholders

[Description of error here]

Another error message here

[Description of error here]

[Et cetera, et cetera]

INCOMPATIBILITIES

None reported.

BUGS AND LIMITATIONS

At the moment it's not possible to compute a DWZ rating for a previously unrated player. Also, every opponent has to have a rating.

Note, that a missing development coefficient (set via $player->set_coefficient()) will probably lead to incorrect results. The program tries to guess the correct factor according to the players rating, but it will err for younger players (less than 25 years old) and for players new to the rating list (with less than six tournaments).

No bugs have been reported.

Please report any bugs or feature requests to bug-games-ratings@rt.cpan.org, or through the web interface at http://rt.cpan.org.

AUTHOR

Christian Bartolomaeus <bartolin@gmx.de>

ACKNOWLEDGMENTS

I have to thank Bernd Schacht -- author of TopTurnier (see http://www.schach-itzehoe.de/TopTurnier/TT95.htm) -- who confirmed that for official rating calculations detailed probability tables are used -- in contrast to the official Wertungsordnung (http://www.schachbund.de/dwz/wo/index.html).

SEE ALSO

http://de.wikipedia.org/wiki/DWZ_(Schach) for general informations about the DWZ rating system.

http://www.schachbund.de/dwz/wo/index.html for technical informations about the DWZ rating system.

LICENCE AND COPYRIGHT

Copyright (c) 2010, Christian Bartolomaeus <bartolin@gmx.de>. All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

cpanm Games::Ratings

perl -MCPAN -e shell
install Games::Ratings