{-
Copyright (C) 2011 Dr. Alistair Ward
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .
-}
{- |
[@AUTHOR@] Dr. Alistair Ward
[@DESCRIPTION@] Defines the /Ramanujan/ series for /Pi/; .
-}
module Factory.Math.Implementations.Pi.Ramanujan.Classic(
-- * Constants
series
) where
--import Control.Arrow((***))
import Data.Ratio((%))
--import Factory.Data.PrimeFactors((>/<), (>^))
--import qualified Factory.Data.PrimeFactors as Data.PrimeFactors
import qualified Factory.Math.Factorial as Math.Factorial
import qualified Factory.Math.Implementations.Factorial as Math.Implementations.Factorial
import qualified Factory.Math.Implementations.Pi.Ramanujan.Series as Math.Implementations.Pi.Ramanujan.Series
import qualified Factory.Math.Power as Math.Power
import qualified Factory.Math.SquareRoot as Math.SquareRoot
-- | Defines the parameters of the /Ramanujan/ series.
series :: (Math.SquareRoot.Algorithm squareRootAlgorithm, Math.Factorial.Algorithm factorialAlgorithm) => Math.Implementations.Pi.Ramanujan.Series.Series squareRootAlgorithm factorialAlgorithm
series = Math.Implementations.Pi.Ramanujan.Series.MkSeries {
Math.Implementations.Pi.Ramanujan.Series.terms = \factorialAlgorithm -> let
toFourthPower = (^ (4 :: Int))
in zipWith (
{-
\n power -> let
product' = Data.PrimeFactors.product' (recip 2) 10
in uncurry (%) . (
(* (1103 + 26390 * n)) . product' *** (* power) . product'
) $ Math.Implementations.Factorial.primeFactors (4 * n) >/< Math.Implementations.Factorial.primeFactors n >^ 4
-}
\n power -> (
Math.Implementations.Factorial.risingFactorial (n + 1) (3 * n) % Math.Power.cube (Math.Factorial.factorial factorialAlgorithm n)
) * (
(1103 + 26390 * n) % power
) -- CAVEAT: the order in which these terms are evaluated radically affects performance.
) [0 ..] $ iterate (* toFourthPower 396) 1,
Math.Implementations.Pi.Ramanujan.Series.getSeriesScalingFactor = \squareRootAlgorithm decimalDigits -> 9801 / Math.SquareRoot.squareRoot squareRootAlgorithm decimalDigits (8 :: Integer),
Math.Implementations.Pi.Ramanujan.Series.convergenceRate = 10 ** negate 7.9 --Empirical.
}