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| author | Xavier Leroy <xavier.leroy@inria.fr> | 2012-03-23 09:58:22 +0000 |
|---|---|---|
| committer | Xavier Leroy <xavier.leroy@inria.fr> | 2012-03-23 09:58:22 +0000 |
| commit | 90fde3e40e13e0fbcd90e72ca43f481278566d60 (patch) | |
| tree | 83893da10ebdf6f2d896f4dc072dc4c5d3105a69 /stdlib/random.ml | |
| parent | 875aab099eacef1e89fc6cce349138ca50b09cce (diff) | |
Updated documentation of Random.self_init and Random.float.
Faster implementation of Random.float: to get a 53-bit random mantissa, combining two calls to Random.bits is enough, three was overkill.
git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@12262 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
Diffstat (limited to 'stdlib/random.ml')
| -rw-r--r-- | stdlib/random.ml | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/stdlib/random.ml b/stdlib/random.ml index aa47536ba..50b570822 100644 --- a/stdlib/random.ml +++ b/stdlib/random.ml @@ -130,13 +130,12 @@ module State = struct else fun s bound -> Int64.to_nativeint (int64 s (Int64.of_nativeint bound)) ;; - (* Returns a float 0 <= x < 1 with at most 90 bits of precision. *) + (* Returns a float 0 <= x <= 1 with at most 60 bits of precision. *) let rawfloat s = - let scale = 1073741824.0 - and r0 = Pervasives.float (bits s) + let scale = 1073741824.0 (* 2^30 *) and r1 = Pervasives.float (bits s) and r2 = Pervasives.float (bits s) - in ((r0 /. scale +. r1) /. scale +. r2) /. scale + in (r1 /. scale +. r2) /. scale ;; let float s bound = rawfloat s *. bound;; |