Issue #3366:  Add gamma function to math module.
(lgamma, erf and erfc to follow).
diff --git a/Doc/library/math.rst b/Doc/library/math.rst
index 96ea91a..d46014b 100644
--- a/Doc/library/math.rst
+++ b/Doc/library/math.rst
@@ -308,6 +308,16 @@
    Return the hyperbolic tangent of *x*.
 
 
+Special functions
+-----------------
+
+.. function:: gamma(x)
+
+   Return the Gamma function at *x*.
+
+   .. versionadded:: 2.7
+
+
 Constants
 ---------