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:class:`numbers.Rational` and is immutable and hashable.
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.. method:: Fraction.from_float(flt)
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This classmethod constructs a :class:`Fraction` representing the
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exact value of *flt*, which must be a :class:`float`. Beware that
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``Fraction.from_float(0.3)`` is not the same value as ``Fraction(3,
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.. method:: Fraction.from_decimal(dec)
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This classmethod constructs a :class:`Fraction` representing the
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exact value of *dec*, which must be a
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:class:`decimal.Decimal`.
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.. method:: Fraction.limit_denominator(max_denominator=1000000)
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Finds and returns the closest :class:`Fraction` to ``self`` that
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has denominator at most max_denominator. This method is useful for
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finding rational approximations to a given floating-point number:
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>>> from fractions import Fraction
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>>> Fraction('3.1415926535897932').limit_denominator(1000)
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or for recovering a rational number that's represented as a float:
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>>> from math import pi, cos
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>>> Fraction.from_float(cos(pi/3))
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Fraction(4503599627370497L, 9007199254740992L)
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>>> Fraction.from_float(cos(pi/3)).limit_denominator()
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.. method:: Fraction.__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:: Fraction.__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:: Fraction.__round__()
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Fraction.__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 ``Fraction(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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.. method:: from_float(flt)
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This classmethod constructs a :class:`Fraction` representing the exact
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value of *flt*, which must be a :class:`float`. Beware that
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``Fraction.from_float(0.3)`` is not the same value as ``Fraction(3, 10)``
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.. method:: from_decimal(dec)
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This classmethod constructs a :class:`Fraction` representing the exact
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value of *dec*, which must be a :class:`decimal.Decimal`.
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.. method:: limit_denominator(max_denominator=1000000)
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Finds and returns the closest :class:`Fraction` to ``self`` that has
50
denominator at most max_denominator. This method is useful for finding
51
rational approximations to a given floating-point number:
53
>>> from fractions import Fraction
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>>> Fraction('3.1415926535897932').limit_denominator(1000)
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or for recovering a rational number that's represented as a float:
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>>> from math import pi, cos
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>>> Fraction.from_float(cos(pi/3))
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Fraction(4503599627370497L, 9007199254740992L)
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>>> Fraction.from_float(cos(pi/3)).limit_denominator()
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.. method:: __floor__()
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Returns the greatest :class:`int` ``<= self``. Will be accessible through
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:func:`math.floor` in Py3k.
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.. method:: __ceil__()
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Returns the least :class:`int` ``>= self``. Will be accessible through
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:func:`math.ceil` in Py3k.
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.. method:: __round__()
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The first version returns the nearest :class:`int` to ``self``, rounding
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half to even. The second version rounds ``self`` to the nearest multiple
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of ``Fraction(1, 10**ndigits)`` (logically, if ``ndigits`` is negative),
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again rounding half toward even. Will be accessible through :func:`round`
added
removed
Doc/library/fractions.rst
