Import Upstream version 2d2upstream/2d2

1 files changed, 15 insertions, 13 deletions

diff --git a/randinex.scm b/randinex.scm
index 8a0afd1..19b9d81 100644
--- a/randinex.scm
+++ b/randinex.scm
@@ -1,9 +1,9 @@
 ;;;"randinex.scm" Pseudo-Random inexact real numbers for scheme.
-;;; Copyright (C) 1991, 1993, 1999 Aubrey Jaffer.
+;;; Copyright (C) 1991, 1993, 1999 Aubrey Jaffer
 ;
-;Permission to copy this software, to redistribute it, and to use it
-;for any purpose is granted, subject to the following restrictions and
-;understandings.
+;Permission to copy this software, to modify it, to redistribute it,
+;to distribute modified versions, and to use it for any purpose is
+;granted, subject to the following restrictions and understandings.
 ;
 ;1.  Any copy made of this software must include this copyright notice
 ;in full.
@@ -70,6 +70,8 @@
 ;;; 1-exp(-r^2/2).  This latter means that u=exp(-r^2/2) is uniformly
 ;;; distributed on [0,1], so r=sqrt(-2 log u) can be used to generate r.
 
+(define *2pi (* 8 (atan 1)))
+
 ;;@args vect
 ;;@args vect state
 ;;Fills @1 with inexact real random numbers which are independent
@@ -82,7 +84,7 @@
 		 (set! sum2 (+ sum2 (* x x))))))
       (do ((n (- (vector-length vect) 1) (- n 2)))
 	  ((negative? n) sum2)
-	(let ((t (* 6.28318530717958 (random:uniform1 state)))
+	(let ((t (* *2pi (random:uniform1 state)))
 	      (r (sqrt (* -2 (log (random:uniform1 state))))))
 	  (do! n (* r (cos t)))
 	  (if (positive? n) (do! (- n 1) (* r (sin t)))))))))
@@ -94,10 +96,9 @@
 ;;@args vect
 ;;@args vect state
 ;;Fills @1 with inexact real random numbers the sum of whose
-;;squares is less than 1.0.  Thinking of @1 as coordinates in
-;;space of dimension @var{n} = @code{(vector-length @1)}, the
-;;coordinates are uniformly distributed within the unit @var{n}-shere.
-;;The sum of the squares of the numbers is returned.
+;;squares is equal to 1.0.  Thinking of @1 as coordinates in space
+;;of dimension n = @code{(vector-length @1)}, the coordinates are
+;;uniformly distributed over the surface of the unit n-shere.
 (define (random:hollow-sphere! vect . args)
   (let ((ms (sqrt (apply random:normal-vector! vect args))))
     (do ((n (- (vector-length vect) 1) (- n 1)))
@@ -113,13 +114,14 @@
 ;;@args vect
 ;;@args vect state
 ;;Fills @1 with inexact real random numbers the sum of whose
-;;squares is equal to 1.0.  Thinking of @1 as coordinates in space
-;;of dimension n = @code{(vector-length @1)}, the coordinates are
-;;uniformly distributed over the surface of the unit n-shere.
+;;squares is less than 1.0.  Thinking of @1 as coordinates in
+;;space of dimension @var{n} = @code{(vector-length @1)}, the
+;;coordinates are uniformly distributed within the unit @var{n}-shere.
+;;The sum of the squares of the numbers is returned.
 (define (random:solid-sphere! vect . args)
   (apply random:hollow-sphere! vect args)
   (let ((r (expt (random:uniform1 (if (null? args) *random-state* (car args)))
 		 (/ (vector-length vect)))))
     (do ((n (- (vector-length vect) 1) (- n 1)))
-	((negative? n))
+	((negative? n) r)
       (vector-set! vect n (* r (vector-ref vect n))))))