{-# LANGUAGE BangPatterns #-}

import qualified Data.Vector.Unboxed as V
import Math.Statistics.Fusion

import Data.List
import Test.QuickCheck


------------------------------------------------------------------------

prop_mean ds = mean (V.fromList ds) == model_mean ds
    where
        model_mean :: Floating a => [a] -> a
        model_mean x = fst $ foldl' (\(!m, !n) x -> (m+(x-m)/(n+1),n+1)) (0,0) x

------------------------------------------------------------------------

prop_harmonic ds = not (null ds) ==> harmonic (V.fromList ds) == model_harmonic ds
    where
        model_harmonic :: (Floating a) => [a] -> a
        model_harmonic xs = fromIntegral (length xs) / (sum $ map (1/) xs)

------------------------------------------------------------------------

prop_geometric ds = not (null ds) ==> geometric (V.fromList ds) == model_geometric ds
    where
        model_geometric :: (Floating a) => [a] -> a
        model_geometric xs = (foldr1 (*) xs)**(1 / fromIntegral (length xs))