Backport PEP 3141 from the py3k branch to the trunk. This includes r50877 (just

the complex_pow part), r56649, r56652, r56715, r57296, r57302, r57359, r57361,
r57372, r57738, r57739, r58017, r58039, r58040, and r59390, and new
documentation. The only significant difference is that round(x) returns a float
to preserve backward-compatibility. See http://bugs.python.org/issue1689.

Doc/reference/datamodel.rst

@@ -150,7 +150,7 @@ Ellipsis
    indicate the presence of the ``...`` syntax in a slice.  Its truth value is
    true.
 
-Numbers
+:class:`numbers.Number`
    .. index:: object: numeric
 
    These are created by numeric literals and returned as results by arithmetic
@@ -162,7 +162,7 @@ Numbers
    Python distinguishes between integers, floating point numbers, and complex
    numbers:
 
-   Integers
+   :class:`numbers.Integral`
       .. index:: object: integer
 
       These represent elements from the mathematical set of integers (positive and
@@ -214,7 +214,7 @@ Numbers
       without causing overflow, will yield the same result in the long integer domain
       or when using mixed operands.
 
-   Floating point numbers
+   :class:`numbers.Real` (:class:`float`)
       .. index::
          object: floating point
          pair: floating point; number
@@ -229,7 +229,7 @@ Numbers
       overhead of using objects in Python, so there is no reason to complicate the
       language with two kinds of floating point numbers.
 
-   Complex numbers
+   :class:`numbers.Complex`
       .. index::
          object: complex
          pair: complex; number

Doc/reference/expressions.rst

@@ -801,7 +801,8 @@ were of integer types and the second argument was negative, an exception was
 raised).
 
 Raising ``0.0`` to a negative power results in a :exc:`ZeroDivisionError`.
-Raising a negative number to a fractional power results in a :exc:`ValueError`.
+Raising a negative number to a fractional power results in a :class:`complex`
+number. (Since Python 2.6. In earlier versions it raised a :exc:`ValueError`.)
 
 
 .. _unary: