4 files changed, 151 insertions, 12 deletions
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index 49fd77d..48efff5 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -915,10 +915,13 @@ available.  They are listed here in alphabetical order.
 .. function:: round(x[, n])
 
    Return the floating point value *x* rounded to *n* digits after the decimal
-   point.  If *n* is omitted, it defaults to zero. The result is a floating point
-   number.  Values are rounded to the closest multiple of 10 to the power minus
-   *n*; if two multiples are equally close, rounding is done away from 0 (so. for
-   example, ``round(0.5)`` is ``1.0`` and ``round(-0.5)`` is ``-1.0``).
+   point.  If *n* is omitted, it defaults to zero.  Values are rounded to the
+   closest multiple of 10 to the power minus *n*; if two multiples are equally
+   close, rounding is done toward the even choice (so, for example, both
+   ``round(0.5)`` and ``round(-0.5)`` are ``0``, and ``round(1.5)`` is
+   ``2``). Delegates to ``x.__round__(n)``.
+
+   .. versionchanged:: 2.6
 
 
 .. function:: set([iterable])
@@ -1064,6 +1067,14 @@ available.  They are listed here in alphabetical order.
    operators such as ``super(C, self)[name]``.
 
 
+.. function:: trunc(x)
+
+   Return the :class:`Real` value *x* truncated to an :class:`Integral` (usually
+   a long integer). Delegates to ``x.__trunc__()``.
+
+   .. versionadded:: 2.6
+
+
 .. function:: tuple([iterable])
 
    Return a tuple whose items are the same and in the same order as *iterable*'s
diff --git a/Doc/library/math.rst b/Doc/library/math.rst
index 7ea4aac..dc8c74a 100644
--- a/Doc/library/math.rst
+++ b/Doc/library/math.rst
@@ -26,8 +26,17 @@ Number-theoretic and representation functions:
 
 .. function:: ceil(x)
 
-   Return the ceiling of *x* as a float, the smallest integer value greater than or
-   equal to *x*.
+   Return the ceiling of *x* as a float, the smallest integer value greater than
+   or equal to *x*. If *x* is not a float, delegates to ``x.__ceil__()``, which
+   should return an :class:`Integral` value.
+
+
+.. function:: copysign(x, y)
+
+   Return *x* with the sign of *y*. ``copysign`` copies the sign bit of an IEEE
+   754 float, ``copysign(1, -0.0)`` returns *-1.0*.
+
+   ..versionadded:: 2.6
 
 
 .. function:: fabs(x)
@@ -37,8 +46,9 @@ Number-theoretic and representation functions:
 
 .. function:: floor(x)
 
-   Return the floor of *x* as a float, the largest integer value less than or equal
-   to *x*.
+   Return the floor of *x* as a float, the largest integer value less than or
+   equal to *x*. If *x* is not a float, delegates to ``x.__floor__()``, which
+   should return an :class:`Integral` value.
 
 
 .. function:: fmod(x, y)
@@ -64,6 +74,23 @@ Number-theoretic and representation functions:
    apart" the internal representation of a float in a portable way.
 
 
+.. function:: isinf(x)
+
+   Checks if the float *x* is positive or negative infinite.
+
+   ..versionadded:: 2.6
+
+
+.. function:: isnan(x)
+
+   Checks if the float *x* is a NaN (not a number). NaNs are part of the
+   IEEE 754 standards. Operation like but not limited to ``inf * 0``, 
+   ``inf / inf`` or any operation involving a NaN, e.g. ``nan * 1``, return
+   a NaN.
+
+   ..versionadded:: 2.6
+
+
 .. function:: ldexp(x, i)
 
    Return ``x * (2**i)``.  This is essentially the inverse of function
diff --git a/Doc/library/numbers.rst b/Doc/library/numbers.rst
new file mode 100644
index 0000000..d0f9c3b
--- /dev/null
+++ b/Doc/library/numbers.rst
@@ -0,0 +1,99 @@
+
+:mod:`numbers` --- Numeric abstract base classes
+================================================
+
+.. module:: numbers
+   :synopsis: Numeric abstract base classes (Complex, Real, Integral, etc.).
+
+The :mod:`numbers` module (:pep:`3141`) defines a hierarchy of numeric abstract
+base classes which progressively define more operations. These concepts also
+provide a way to distinguish exact from inexact types. None of the types defined
+in this module can be instantiated.
+
+
+.. class:: Number
+
+   The root of the numeric hierarchy. If you just want to check if an argument
+   *x* is a number, without caring what kind, use ``isinstance(x, Number)``.
+
+
+Exact and inexact operations
+----------------------------
+
+.. class:: Exact
+
+   Subclasses of this type have exact operations.
+
+   As long as the result of a homogenous operation is of the same type, you can
+   assume that it was computed exactly, and there are no round-off errors. Laws
+   like commutativity and associativity hold.
+
+
+.. class:: Inexact
+
+   Subclasses of this type have inexact operations.
+
+   Given X, an instance of :class:`Inexact`, it is possible that ``(X + -X) + 3
+   == 3``, but ``X + (-X + 3) == 0``. The exact form this error takes will vary
+   by type, but it's generally unsafe to compare this type for equality.
+
+
+The numeric tower
+-----------------
+
+.. class:: Complex
+
+   Subclasses of this type describe complex numbers and include the operations
+   that work on the builtin :class:`complex` type. These are: conversions to
+   :class:`complex` and :class:`bool`, :attr:`.real`, :attr:`.imag`, ``+``,
+   ``-``, ``*``, ``/``, :func:`abs`, :meth:`conjugate`, ``==``, and ``!=``. All
+   except ``-`` and ``!=`` are abstract.
+
+.. attribute:: Complex.real
+
+   Abstract. Retrieves the :class:`Real` component of this number.
+
+.. attribute:: Complex.imag
+
+   Abstract. Retrieves the :class:`Real` component of this number.
+
+.. method:: Complex.conjugate()
+
+   Abstract. Returns the complex conjugate. For example, ``(1+3j).conjugate() ==
+   (1-3j)``.
+
+.. class:: Real
+
+   To :class:`Complex`, :class:`Real` adds the operations that work on real
+   numbers.
+
+   In short, those are: a conversion to :class:`float`, :func:`trunc`,
+   :func:`round`, :func:`math.floor`, :func:`math.ceil`, :func:`divmod`, ``//``,
+   ``%``, ``<``, ``<=``, ``>``, and ``>=``.
+
+   Real also provides defaults for :func:`complex`, :attr:`Complex.real`,
+   :attr:`Complex.imag`, and :meth:`Complex.conjugate`.
+
+
+.. class:: Rational
+
+   Subtypes both :class:`Real` and :class:`Exact`, and adds
+   :attr:`Rational.numerator` and :attr:`Rational.denominator` properties, which
+   should be in lowest terms. With these, it provides a default for
+   :func:`float`.
+
+.. attribute:: Rational.numerator
+
+   Abstract.
+
+.. attribute:: Rational.denominator
+
+   Abstract.
+
+
+.. class:: Integral
+
+   Subtypes :class:`Rational` and adds a conversion to :class:`long`, the
+   3-argument form of :func:`pow`, and the bit-string operations: ``<<``,
+   ``>>``, ``&``, ``^``, ``|``, ``~``. Provides defaults for :func:`float`,
+   :attr:`Rational.numerator`, and :attr:`Rational.denominator`.
diff --git a/Doc/library/numeric.rst b/Doc/library/numeric.rst
index 0d9d59f..d2b4d8b 100644
--- a/Doc/library/numeric.rst
+++ b/Doc/library/numeric.rst
@@ -6,16 +6,18 @@ Numeric and Mathematical Modules
 ********************************
 
 The modules described in this chapter provide numeric and math-related functions
-and data types. The :mod:`math` and :mod:`cmath` contain  various mathematical
-functions for floating-point and complex numbers. For users more interested in
-decimal accuracy than in speed, the  :mod:`decimal` module supports exact
-representations of  decimal numbers.
+and data types. The :mod:`numbers` module defines an abstract hierarchy of
+numeric types. The :mod:`math` and :mod:`cmath` modules contain various
+mathematical functions for floating-point and complex numbers. For users more
+interested in decimal accuracy than in speed, the :mod:`decimal` module supports
+exact representations of decimal numbers.
 
 The following modules are documented in this chapter:
 
 
 .. toctree::
 
+   numbers.rst
    math.rst
    cmath.rst
    decimal.rst