From: Mark Dickinson Date: Wed, 7 Jan 2009 17:54:07 +0000 (+0000) Subject: Merged revisions 68378 via svnmerge from X-Git-Tag: v3.1a1~563 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=2f947369b37c8f16f882a9c426245193a1801bbd;p=python Merged revisions 68378 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r68378 | mark.dickinson | 2009-01-07 17:48:33 +0000 (Wed, 07 Jan 2009) | 2 lines Issue #4869: clarify documentation for random.expovariate. ........ --- diff --git a/Doc/library/random.rst b/Doc/library/random.rst index da0e6632f3..82d2555cee 100644 --- a/Doc/library/random.rst +++ b/Doc/library/random.rst @@ -169,9 +169,11 @@ be found in any statistics text. .. function:: expovariate(lambd) - Exponential distribution. *lambd* is 1.0 divided by the desired mean. (The - parameter would be called "lambda", but that is a reserved word in Python.) - Returned values range from 0 to positive infinity. + Exponential distribution. *lambd* is 1.0 divided by the desired + mean. It should be nonzero. (The parameter would be called + "lambda", but that is a reserved word in Python.) Returned values + range from 0 to positive infinity if *lambd* is positive, and from + negative infinity to 0 if *lambd* is negative. .. function:: gammavariate(alpha, beta) diff --git a/Lib/random.py b/Lib/random.py index 70603ca2ae..95f44113bf 100644 --- a/Lib/random.py +++ b/Lib/random.py @@ -396,9 +396,11 @@ class Random(_random.Random): def expovariate(self, lambd): """Exponential distribution. - lambd is 1.0 divided by the desired mean. (The parameter would be - called "lambda", but that is a reserved word in Python.) Returned - values range from 0 to positive infinity. + lambd is 1.0 divided by the desired mean. It should be + nonzero. (The parameter would be called "lambda", but that is + a reserved word in Python.) Returned values range from 0 to + positive infinity if lambd is positive, and from negative + infinity to 0 if lambd is negative. """ # lambd: rate lambd = 1/mean