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:mod:`rational` --- Rational numbers
====================================
.. module:: rational
:synopsis: Rational numbers.
.. moduleauthor:: Jeffrey Yasskin <jyasskin at gmail.com>
.. sectionauthor:: Jeffrey Yasskin <jyasskin at gmail.com>
.. versionadded:: 2.6
The :mod:`rational` module defines an immutable, infinite-precision
Rational number class.
.. class:: Rational(numerator=0, denominator=1)
Rational(other_rational)
Rational(string)
The first version requires that *numerator* and *denominator* are
instances of :class:`numbers.Integral` and returns a new
``Rational`` representing ``numerator/denominator``. If
*denominator* is :const:`0`, raises a :exc:`ZeroDivisionError`. The
second version requires that *other_rational* is an instance of
:class:`numbers.Rational` and returns an instance of
:class:`Rational` with the same value. The third version expects a
string of the form ``[-+]?[0-9]+(/[0-9]+)?``, optionally surrounded
by spaces.
Implements all of the methods and operations from
:class:`numbers.Rational` and is immutable and hashable.
.. method:: Rational.from_float(flt)
This classmethod constructs a :class:`Rational` representing the
exact value of *flt*, which must be a :class:`float`. Beware that
``Rational.from_float(0.3)`` is not the same value as ``Rational(3,
10)``
.. method:: Rational.from_decimal(dec)
This classmethod constructs a :class:`Rational` representing the
exact value of *dec*, which must be a
:class:`decimal.Decimal`.
.. method:: Rational.__floor__()
Returns the greatest :class:`int` ``<= self``. Will be accessible
through :func:`math.floor` in Py3k.
.. method:: Rational.__ceil__()
Returns the least :class:`int` ``>= self``. Will be accessible
through :func:`math.ceil` in Py3k.
.. method:: Rational.__round__()
Rational.__round__(ndigits)
The first version returns the nearest :class:`int` to ``self``,
rounding half to even. The second version rounds ``self`` to the
nearest multiple of ``Rational(1, 10**ndigits)`` (logically, if
``ndigits`` is negative), again rounding half toward even. Will be
accessible through :func:`round` in Py3k.
.. seealso::
Module :mod:`numbers`
The abstract base classes making up the numeric tower.
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