= ICU Chess Ratings

For calculating the Elo ratings of players in a chess tournament. The software is a port
the Irish Chess Union's existing rating software written in Microsoft Visual Basic and
intended to replace it in the near future.

The rating calculations are identical to FIDE's for tournaments that consist entirely
of established players (with the exception of player bonuses, which can be turned off).
However, the ICU has it's own peculiar way of dealing with unrated players (players
with only a provisional rating or without any prior rating) which is not the same as
FIDE's.

== Install

  sudo gem install icu_ratings

Tested with ruby 1.8.7 and 1.9.2.

== Usage

First, create a new ICU::RatedTournament object:

  t = ICU::RatedTournament.new(:desc => "Irish Championships 2008")

Then add players (see ICU::RatedPlayer for details):

  t.add_player(1, :rating => 2534, :desc => 'Alexander Baburin (7085)', :kfactor => 16)
  t.add_player(2, :rating => 2525, :desc => 'Alon Greenfeld')  # foreign (non-ICU) rated player
  t.add_player(8, :rating => 2084, :desc => 'Anthony Fox (456)', :kfactor => 24)
  # ...

Then add results (see ICU::RatedResult for details):

  t.add_result(1, 1, 8, 'W')    # players 1 and 8 played in round 1, player 1 won
  t.add_result(4, 2, 1, 'D')    # players 1 and 2 drew in round 4
  # ...

Then call the <em>rate!</em> method.

  t.rate!

If no exceptions have been raised yet, the tournament is now rated and the
main results of the rating calculations can be extracted by querying the
previously created player objects:

  (1..32).each do |num|
    player = t.player(num)
    puts "Name: #{t.desc}"
    puts "Score: #{p.score}/#{p.results.size}"
    puts "New Rating: #{p.new_rating.round}"
    puts "Performance Rating: #{p.performance.round}"
  end
  
  # Name: Alexander Baburin (7085)
  # Score: 8.0/9
  # New Rating: 2558
  # Performance Rating: 2607
  # ...

See ICU::RatedPlayer for further details. Further breakdown of the rating calculations
are available, if desired, from the results belonging to each player. See ICU::RatedResult
for more details.

== Author

Mark Orr, Irish Chess Union (ICU[http://icu.ie]) rating officer.