Issue 10787: Document the probability density function for random.gammavariate.
diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst
index 12dc4d8..b7137c9 100644
--- a/Doc/reference/datamodel.rst
+++ b/Doc/reference/datamodel.rst
@@ -1540,10 +1540,10 @@
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 01e1420..dcc79d1 100644
--- a/Lib/random.py
+++ b/Lib/random.py
@@ -490,6 +490,12 @@
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