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