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//-----------------------------------------------------------------------------
/** @file libboardgame_base/Rating.cpp
@author Markus Enzenberger
@copyright GNU General Public License version 3 or later */
//-----------------------------------------------------------------------------
#include "Rating.h"
#include <iostream>
#include "Assert.h"
namespace libboardgame_base {
//-----------------------------------------------------------------------------
ostream& operator<<(ostream& out, Rating rating)
{
out << rating.m_elo;
return out;
}
istream& operator>>(istream& in, Rating& rating)
{
in >> rating.m_elo;
return in;
}
double Rating::get_expected_result(Rating elo_opponent,
unsigned nu_opponents) const
{
auto diff = elo_opponent.m_elo - m_elo;
return
1. / (1. + static_cast<double>(nu_opponents) * pow(10., diff / 400.));
}
void Rating::update(double game_result, Rating elo_opponent, double k_value,
unsigned nu_opponents)
{
LIBBOARDGAME_ASSERT(k_value > 0);
auto diff = game_result - get_expected_result(elo_opponent, nu_opponents);
m_elo += k_value * diff;
}
//-----------------------------------------------------------------------------
} // namespace libboardgame_base
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