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module Probability.Distribution.Geometric where
import Probability.Random
import MCMC
--foreign import bpcall "Distribution:geometric_density" geometric_density :: Double -> Double -> Int -> LogDouble
foreign import bpcall "Distribution:" sample_geometric :: Double -> IO Int
data Geometric = Geometric Prob
instance Dist Geometric where
type Result Geometric = Int
dist_name _ = "geometric"
instance IOSampleable Geometric where
sampleIO (Geometric p_success) = sample_geometric (toFloating p_success)
-- Hmm.. Maybe we want the result of discrete distributionts to be Probability instead of LogDouble?
instance HasPdf Geometric where
pdf (Geometric p_success) n | n < 0 = 0
| otherwise = toFloating $ p_success * pow (1-p_success) (fromIntegral n)
instance Dist1D Geometric where
cdf (Geometric p_success) n = undefined
lower_bound dist = Just 0
instance MaybeMean Geometric where
maybeMean (Geometric p) = Just $ toFloating $ (1-p)/p
instance Mean Geometric
instance MaybeVariance Geometric where
maybeVariance (Geometric p) = Just $ toFloating $ (1-p)/(p*p)
instance Variance Geometric
instance HasAnnotatedPdf Geometric where
annotated_densities dist@(Geometric p_success) n = do
in_edge "p_success" p_success
return ([pdf dist n],())
instance Sampleable Geometric where
sample dist@(Geometric p_success) = RanDistribution2 dist geometric_effect
geometric_bounds = integer_above 0
geometric_effect x = do
add_move $ sliceSampleInteger x geometric_bounds
add_move $ incDecMH x geometric_bounds
{- NOTE: Why specify that pSuccess :: Double ?
This avoids callers of (geometric p) getting
saddled with ambiguous types.
See note in Data.Floating.Types
-}
geometric :: Double -> Geometric
geometric pSuccess = Geometric (toFloating pSuccess)
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