ClimbHome: Change misleading Seed assignment to nil value
This was "Seed = ClimbHome", but ClimbHome was a nil value.
This code still worked as the engine interpreted the nil value as empty string.
But it can be very misleading.
This changeset makes the Seed assignment more explicit by assigning the empty string directly.
The compability has been tested.
{-
Glicko2, as described in http://www.glicko.net/glicko/glicko2.pdf
-}
module OfficialServer.Glicko2 where
data RatingData = RatingData {
ratingValue
, rD
, volatility :: Double
}
data GameData = GameData {
opponentRating :: RatingData,
gameScore :: Double
}
τ, ε :: Double
τ = 0.2
ε = 0.000001
g_φ :: Double -> Double
g_φ φ = 1 / sqrt (1 + 3 * φ^2 / pi^2)
calcE :: RatingData -> GameData -> (Double, Double, Double)
calcE oldRating (GameData oppRating s) = (
1 / (1 + exp (g_φᵢ * (μᵢ - μ)))
, g_φᵢ
, s
)
where
μ = (ratingValue oldRating - 1500) / 173.7178
φ = rD oldRating / 173.7178
μᵢ = (ratingValue oppRating - 1500) / 173.7178
φᵢ = rD oppRating / 173.7178
g_φᵢ = g_φ φᵢ
calcNewRating :: RatingData -> [GameData] -> (Int, RatingData)
calcNewRating oldRating [] = (0, RatingData (ratingValue oldRating) (173.7178 * sqrt (φ ^ 2 + σ ^ 2)) σ)
where
φ = rD oldRating / 173.7178
σ = volatility oldRating
calcNewRating oldRating games = (length games, RatingData (173.7178 * μ' + 1500) (173.7178 * sqrt φ'sqr) σ')
where
_Es = map (calcE oldRating) games
υ = 1 / sum (map υ_p _Es)
υ_p (_Eᵢ, g_φᵢ, _) = g_φᵢ ^ 2 * _Eᵢ * (1 - _Eᵢ)
_Δ = υ * part1
part1 = sum (map _Δ_p _Es)
_Δ_p (_Eᵢ, g_φᵢ, sᵢ) = g_φᵢ * (sᵢ - _Eᵢ)
μ = (ratingValue oldRating - 1500) / 173.7178
φ = rD oldRating / 173.7178
σ = volatility oldRating
a = log (σ ^ 2)
f :: Double -> Double
f x = exp x * (_Δ ^ 2 - φ ^ 2 - υ - exp x) / 2 / (φ ^ 2 + υ + exp x) ^ 2 - (x - a) / τ ^ 2
_A = a
_B = if _Δ ^ 2 > φ ^ 2 + υ then log (_Δ ^ 2 - φ ^ 2 - υ) else head . dropWhile ((>) 0 . f) . map (\k -> a - k * τ) $ [1 ..]
fA = f _A
fB = f _B
σ' = (\(_A, _, _, _) -> exp (_A / 2)) . head . dropWhile (\(_A, _, _B, _) -> abs (_B - _A) > ε) $ iterate step5 (_A, fA, _B, fB)
step5 (_A, fA, _B, fB) = let _C = _A + (_A - _B) * fA / (fB - fA); fC = f _C in
if fC * fB < 0 then (_B, fB, _C, fC) else (_A, fA / 2, _C, fC)
φ'sqr = 1 / (1 / (φ ^ 2 + σ' ^ 2) + 1 / υ)
μ' = μ + φ'sqr * part1