public ScorePlayer Calculate(ScorePlayer player, IEnumerable <Tuple <ScorePlayer, double> > opponents, double factor = 1.0)
{
// Step 3
double v = 0.0;
foreach (var opponent in opponents)
{
var e = this.E(player.RatingScaled, opponent.Item1.RatingScaled, opponent.Item1.RdScaled);
v += Math.Pow(this.G(opponent.Item1.RdScaled), 2) * e * (1 - e);
}
v = Math.Pow(v, -1.0);
// Step 4
double delta = 0.0;
foreach (var opponent in opponents)
{
delta += this.G(opponent.Item1.RdScaled) * (opponent.Item2 - this.E(player.RatingScaled, opponent.Item1.RatingScaled, opponent.Item1.RdScaled));
}
delta *= v;
// Step 5
const double epsilon = 0.000001;
double A, a, B;
A = a = Math.Log(Math.Pow(player.Vol, 2));
var delta2 = delta * delta;
var rd2 = player.RdScaled * player.RdScaled;
if (delta2 > rd2 + v)
{
B = Math.Log(delta2 - rd2 - v);
}
else
{
int k = 0;
while (this.F(delta, a, player.RdScaled, v, a - k * Config.Tau) < 0)
{
++k;
}
B = a - k * Config.Tau;
}
// Step 5.3
double fa = this.F(delta, a, player.RdScaled, v, A);
double fb = this.F(delta, a, player.RdScaled, v, B);
// Step 5.4
while (Math.Abs(B - A) > epsilon)
{
double C = A + (A - B) * fa / (fb - fa);
double fc = this.F(delta, a, player.RdScaled, v, C);
if (fc * fb < 0)
{
A = B;
fa = fb;
}
else
{
fa = fa / 2.0;
}
B = C;
fb = fc;
}
// Step 5.5
double vol1 = Math.Pow(Math.E, A / 2.0);
// Step 6
double rdstar = Math.Sqrt(rd2 + vol1 * vol1);
// Step 7
double rdnew = 1.0 / Math.Sqrt(1 / (rdstar * rdstar) + 1 / v);
double ratingnew = 0.0;
foreach (var opponent in opponents)
{
ratingnew += (rdnew * rdnew) * this.G(opponent.Item1.RatingScaled) * (opponent.Item2 - this.E(player.RatingScaled, opponent.Item1.RatingScaled, opponent.Item1.RdScaled));
}
// Step 8
var result = new ScorePlayer(player.Id);
result.RatingScaled = player.RatingScaled + ratingnew * factor;
result.RdScaled = (rdnew - player.RdScaled) * factor + player.RdScaled;
return(result);
}
public ScorePlayer Calculate(ScorePlayer player, IEnumerable<Tuple<ScorePlayer, double>> opponents, double factor = 1.0)
{
// Step 3
double v = 0.0;
foreach(var opponent in opponents)
{
var e = this.E(player.RatingScaled, opponent.Item1.RatingScaled, opponent.Item1.RdScaled);
v += Math.Pow(this.G(opponent.Item1.RdScaled), 2) * e * (1 - e);
}
v = Math.Pow(v, -1.0);
// Step 4
double delta = 0.0;
foreach(var opponent in opponents)
{
delta += this.G(opponent.Item1.RdScaled) * (opponent.Item2 - this.E(player.RatingScaled, opponent.Item1.RatingScaled, opponent.Item1.RdScaled));
}
delta *= v;
// Step 5
const double epsilon = 0.000001;
double A, a, B;
A = a = Math.Log(Math.Pow(player.Vol, 2));
var delta2 = delta * delta;
var rd2 = player.RdScaled * player.RdScaled;
if (delta2 > rd2 + v)
{
B = Math.Log(delta2 - rd2 - v);
}
else
{
int k = 0;
while (this.F(delta, a, player.RdScaled, v, a - k * Config.Tau) < 0)
{
++k;
}
B = a - k * Config.Tau;
}
// Step 5.3
double fa = this.F(delta, a, player.RdScaled, v, A);
double fb = this.F(delta, a, player.RdScaled, v, B);
// Step 5.4
while (Math.Abs(B - A) > epsilon)
{
double C = A + (A - B) * fa / (fb - fa);
double fc = this.F(delta, a, player.RdScaled, v, C);
if (fc * fb < 0)
{
A = B;
fa = fb;
}
else
{
fa = fa / 2.0;
}
B = C;
fb = fc;
}
// Step 5.5
double vol1 = Math.Pow(Math.E, A / 2.0);
// Step 6
double rdstar = Math.Sqrt(rd2 + vol1 * vol1);
// Step 7
double rdnew = 1.0 / Math.Sqrt(1 / (rdstar * rdstar) + 1 / v);
double ratingnew = 0.0;
foreach(var opponent in opponents)
{
ratingnew += (rdnew * rdnew) * this.G(opponent.Item1.RatingScaled) * (opponent.Item2 - this.E(player.RatingScaled, opponent.Item1.RatingScaled, opponent.Item1.RdScaled));
}
// Step 8
var result = new ScorePlayer(player.Id);
result.RatingScaled = player.RatingScaled + ratingnew * factor;
result.RdScaled = (rdnew - player.RdScaled) * factor + player.RdScaled;
return result;
}
