Stop SplitByChar also lowercasing the entire string. Fixes
bug #581.
It's weird that a function with this name would lowercase the whole string.
Nemo and I have checked the history and code for any justifications of the
lowercasing but we found none.
I have checked in the code if anything actually depends on SplitByChar also
lowercasing the string but I found nothing.
It would surprise me since it's not obvious from the name IMO is bad
coding practice anyway.
Bug 581 is fixed by this because cLocale was (incorrectly) lowercased,
which broke locale names like pt_BR to pt_br.
{-
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