[project @ 1996-07-01 09:16:34 by partain]

[ghc-hetmet.git] / ghc / lib / hbc / Random.hs

diff --git a/ghc/lib/hbc/Random.hs b/ghc/lib/hbc/Random.hs
deleted file mode 100644 (file)
index d743876..0000000
--- a/ghc/lib/hbc/Random.hs
+++ /dev/null
@@ -1,59 +0,0 @@
-{-
-   This module implements a (good) random number generator.
-
-   The June 1988 (v31 #6) issue of the Communications of the ACM has an
-   article by Pierre L'Ecuyer called, "Efficient and Portable Combined
-   Random Number Generators".  Here is the Portable Combined Generator of
-   L'Ecuyer for 32-bit computers.  It has a period of roughly 2.30584e18.
-
-   Transliterator: Lennart Augustsson
--}
-
-module Random(randomInts, randomDoubles, normalRandomDoubles) where
--- Use seeds s1 in 1..2147483562 and s2 in 1..2147483398 to generate
--- an infinite list of random Ints.
-randomInts :: Int -> Int -> [Int]
-randomInts s1 s2 =
-    if 1 <= s1 && s1 <= 2147483562 then
-       if 1 <= s2 && s2 <= 2147483398 then
-           rands s1 s2
-       else
-           error "randomInts: Bad second seed."
-    else
-       error "randomInts: Bad first seed."
-
-rands :: Int -> Int -> [Int]
-rands s1 s2 = z' : rands s1'' s2''
-       where   z'   = if z < 1 then z + 2147483562 else z
-               z    = s1'' - s2''
-
-               k    = s1 `quot` 53668
-               s1'  = 40014 * (s1 - k * 53668) - k * 12211
-               s1'' = if s1' < 0 then s1' + 2147483563 else s1'
-    
-               k'   = s2 `quot` 52774
-               s2'  = 40692 * (s2 - k' * 52774) - k' * 3791
-               s2'' = if s2' < 0 then s2' + 2147483399 else s2'
-       
--- Same values for s1 and s2 as above, generates an infinite
--- list of Doubles uniformly distibuted in (0,1).
-randomDoubles :: Int -> Int -> [Double]
-randomDoubles s1 s2 = map (\x -> fromIntegral x * 4.6566130638969828e-10) (randomInts s1 s2)
-
--- The normal distribution stuff is stolen from Tim Lambert's
--- M*****a version
-
--- normalRandomDoubles is given two seeds and returns an infinite list of random
--- normal variates with mean 0 and variance 1.  (Box Muller method see
--- "Art of Computer Programming Vol 2")
-normalRandomDoubles :: Int -> Int -> [Double]
-normalRandomDoubles s1 s2 = boxMuller (map (\x->2*x-1) (randomDoubles s1 s2))
-
--- boxMuller takes a stream of uniform random numbers on [-1,1] and
--- returns a stream of normally distributed random numbers.
-boxMuller :: [Double] -> [Double]
-boxMuller (x1:x2:xs) | r <= 1    = x1*m : x2*m : rest
-                     | otherwise = rest
-                                  where r = x1*x1 + x2*x2
-                                        m = sqrt(-2*log r/r)
-                                        rest = boxMuller xs