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Combinational probability
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import Debug.Trace | |
import System.Environment | |
qnr :: Integer -> Integer -> Double -> Double | |
qnr n r 0 = 0 | |
qnr n r p | |
| n < r = 0 | |
| n == r = q | |
| otherwise = q + (n' - r')*(log(1-p)) + (foldl (+) 0 (map (log) [n'-r'+1..n'])) - (foldl (+) 0 (map log [2..r'])) | |
where n' = fromIntegral n | |
r' = fromIntegral r | |
q = r' * (log p) | |
exp_qnr :: Integer -> Integer -> Double -> Double | |
exp_qnr n r p = exp (qnr n r p) | |
pnr :: Integer -> Integer -> Double -> Double | |
pnr n r 0 = 0 | |
pnr n r p | |
| n < r = 0 | |
| n == r = exp q | |
| otherwise = pnr (n-1) r p + p * exp_qnr (n-1) (r-1) p | |
where q = fromIntegral r * (log p) | |
main = do | |
args <- getArgs | |
(n,r,p) <- case args of | |
n':r':p':_ -> (,,) <$> readIO n' <*> readIO r' <*> readIO p' | |
_ -> return (6400, 64, 0.8) | |
-- putStrLn $ "qnr " ++ show n ++ " " ++ show r ++ " " ++ show p ++ " = " ++ show (exp_qnr n r p) | |
putStrLn $ "pnr " ++ show n ++ " " ++ show r ++ " " ++ show p ++ " = " ++ show (pnr n r p) |
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