diff options
| author | David N. Welton <davidw@efn.org> | 1998-11-09 21:18:01 -0800 |
|---|---|---|
| committer | Bryan Newbold <bnewbold@robocracy.org> | 2017-02-20 00:05:27 -0800 |
| commit | 926b1b647ac830660933a5e63eb52d4a2552e264 (patch) | |
| tree | e25db5f6e1441d67f5d9af063432018ee20a5f51 /randinex.scm | |
| parent | b21cac3362022718634f7086964208b2eed8e897 (diff) | |
| parent | fa3f23105ddcf07c5900de47f19af43d1db1b597 (diff) | |
| download | slib-926b1b647ac830660933a5e63eb52d4a2552e264.tar.gz slib-926b1b647ac830660933a5e63eb52d4a2552e264.zip | |
Import Debian changes 2c3-3debian/2c3-3
slib (2c3-3) frozen unstable; urgency=low
* Fixes #16235.
* Fixes #19943.
* Fixes #20265.
* Fixes #24917.
* Fixes #27389.
slib (2c3-2) frozen unstable; urgency=low
* Re-uploaded for slink freeze.
slib (2c3-1) unstable; urgency=low
* New upstream release.
Diffstat (limited to 'randinex.scm')
| -rw-r--r-- | randinex.scm | 44 |
1 files changed, 20 insertions, 24 deletions
diff --git a/randinex.scm b/randinex.scm index 1c2b702..e6dc48b 100644 --- a/randinex.scm +++ b/randinex.scm @@ -22,28 +22,26 @@ ;;; Fixed sphere and normal functions from: Harald Hanche-Olsen -(define random:float-radix - (+ 1 (exact->inexact random:MASK))) - -;;; This determines how many chunks will be neccessary to completely -;;; fill up an inexact real. -(define (random:size-float l x) - (cond ((= 1.0 (+ 1 x)) l) - ((= 4 l) l) - (else (random:size-float (+ l 1) (/ x random:float-radix))))) -(define random:chunks/float (random:size-float 0 1.0)) - -(define (random:uniform-chunk n state) - (if (= 1 n) - (/ (exact->inexact (random:chunk state)) - random:float-radix) - (/ (+ (random:uniform-chunk (- n 1) state) - (exact->inexact (random:chunk state))) - random:float-radix))) - ;;; Generate an inexact real between 0 and 1. -(define (random:uniform state) - (random:uniform-chunk random:chunks/float state)) +(define random:uniform + (letrec ((random:chunks/float ; how many chunks fill an inexact? + (letrec ((random:size-float + (lambda (l x) + (cond ((= 1.0 (+ 1 x)) l) + ((= 4 l) l) + (else (random:size-float (+ l 1) (/ x 256.0))))))) + (random:size-float 0 1.0))) + + (random:uniform-chunk + (lambda (n state) + (if (= 1 n) + (/ (exact->inexact (random:chunk state)) + 256.0) + (/ (+ (random:uniform-chunk (- n 1) state) + (exact->inexact (random:chunk state))) + 256.0))))) + (lambda (state) + (random:uniform-chunk random:chunks/float state)))) ;;; If x and y are independent standard normal variables, then with ;;; x=r*cos(t), y=r*sin(t), we find that t is uniformly distributed @@ -81,7 +79,7 @@ ;;; For the uniform distribution on the solid sphere, note that in ;;; this distribution the length r of the vector has cumulative -;;; distribution r^n; i.e., u=r^n is uniform [0,1], so r kan be +;;; distribution r^n; i.e., u=r^n is uniform [0,1], so r can be ;;; generated as r=u^(1/n). (define (random:solid-sphere! vect . args) @@ -95,5 +93,3 @@ (define (random:exp . args) (let ((state (if (null? args) *random-state* (car args)))) (- (log (random:uniform state))))) - -(require 'random) |