From 405a4717e1108b95d5af0e61dd304fe6407bd256 Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Tue, 22 Mar 2011 15:52:46 -0700 Subject: [PATCH] Issue 10787: Document the probability density function for random.gammavariate. --- Doc/reference/datamodel.rst | 8 ++++---- Lib/random.py | 6 ++++++ 2 files changed, 10 insertions(+), 4 deletions(-) diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst index 12dc4d8e3c4..b7137c9a40a 100644 --- a/Doc/reference/datamodel.rst +++ b/Doc/reference/datamodel.rst @@ -1540,10 +1540,10 @@ Implementing Descriptors The following methods only apply when an instance of the class containing the method (a so-called *descriptor* class) appears in the class dictionary of -another new-style class, known as the *owner* class. In the examples below, "the -attribute" refers to the attribute whose name is the key of the property in the -owner class' ``__dict__``. Descriptors can only be implemented as new-style -classes themselves. +another new-style class (known as the *owner* class) or one of its +descendants. In the examples below, "the attribute" refers to the attribute +whose name is the key of the property in the owner class' ``__dict__``. +Descriptors can only be implemented as new-style classes themselves. .. method:: object.__get__(self, instance, owner) diff --git a/Lib/random.py b/Lib/random.py index 01e1420df6d..dcc79d1fffd 100644 --- a/Lib/random.py +++ b/Lib/random.py @@ -490,6 +490,12 @@ class Random(_random.Random): Conditions on the parameters are alpha > 0 and beta > 0. + The probability distribution function is: + + x ** (alpha - 1) * math.exp(-x / beta) + pdf(x) = -------------------------------------- + math.gamma(alpha) * beta ** alpha + """ # alpha > 0, beta > 0, mean is alpha*beta, variance is alpha*beta**2