Source code for diofant.domains.rationalfield

"""Implementation of :class:`RationalField` class. """

import math

from ..polys.polyerrors import CoercionFailed
from .characteristiczero import CharacteristicZero
from .field import Field
from .groundtypes import (DiofantRational, GMPYRational, PythonRational,
                          gmpy_factorial, gmpy_qdiv, python_factorial)
from .simpledomain import SimpleDomain


__all__ = 'GMPYRationalField', 'PythonRationalField', 'RationalField'


[docs]class RationalField(Field, CharacteristicZero, SimpleDomain): """General class for rational fields. """ rep = 'QQ' is_RationalField = is_QQ = True is_Numerical = True has_assoc_Ring = True has_assoc_Field = True
[docs] def algebraic_field(self, *extension): r"""Returns an algebraic field, i.e. `\mathbb{Q}(\alpha, \ldots)`. """ from . import AlgebraicField return AlgebraicField(self, *extension)
[docs] def to_expr(self, a): """Convert ``a`` to a Diofant object. """ return DiofantRational(a.numerator, a.denominator)
[docs] def from_expr(self, a): """Convert Diofant's Integer to ``dtype``. """ if a.is_Rational: return self.dtype(a.numerator, a.denominator) elif a.is_Float: from . import RR return self.dtype(*RR.to_rational(a)) else: raise CoercionFailed("expected `Rational` object, got %s" % a)
def _from_PythonIntegerRing(self, a, K0): return self.dtype(a) def _from_PythonRationalField(self, a, K0): return self.dtype(a.numerator, a.denominator) def _from_GMPYIntegerRing(self, a, K0): return self.dtype(int(a)) def _from_GMPYRationalField(self, a, K0): return self.dtype(int(a.numerator), int(a.denominator)) def _from_RealField(self, a, K0): return self.dtype(*K0.to_rational(a)) def _from_AlgebraicField(self, a, K0): if a.is_ground: return self.convert(a.LC(), K0.domain)
[docs] def log(self, a, b): """Returns b-base logarithm of ``a``. """ return self.dtype(int(math.log(int(a), b)))
[docs]class PythonRationalField(RationalField): """Rational field based on Python's rationals. """ dtype = PythonRational zero = dtype(0) one = dtype(1) @property def ring(self): """Returns ring associated with ``self``. """ from .integerring import PythonIntegerRing return PythonIntegerRing() def factorial(self, a): """Returns factorial of `a`. """ return self.dtype(python_factorial(int(a)))
[docs]class GMPYRationalField(RationalField): """Rational field based on GMPY's rationals. """ dtype = GMPYRational zero = dtype(0) one = dtype(1) tp = type(one) @property def ring(self): """Returns ring associated with ``self``. """ from .integerring import GMPYIntegerRing return GMPYIntegerRing() def exquo(self, a, b): """Exact quotient of `a` and `b`, implies `__truediv__`. """ return self.dtype(gmpy_qdiv(a, b)) def quo(self, a, b): """Quotient of `a` and `b`, implies `__truediv__`. """ return self.dtype(gmpy_qdiv(a, b)) def factorial(self, a): """Returns factorial of `a`. """ return self.dtype(gmpy_factorial(int(a)))
QQ_python = PythonRationalField() QQ_gmpy = GMPYRationalField()