Source code for

"""Implementation of :class:`Domain` class. """

import abc
import inspect

from ..core import Expr
from ..core.compatibility import HAS_GMPY
from ..polys.orderings import lex
from ..polys.polyerrors import CoercionFailed, UnificationFailed
from ..polys.polyutils import _unify_gens
from ..printing.defaults import DefaultPrinting
from .domainelement import DomainElement

__all__ = 'Domain',

[docs]class Domain(DefaultPrinting, abc.ABC): """Represents an abstract domain. """ dtype = None zero = None one = None is_Ring = False is_Field = False has_assoc_Ring = False has_assoc_Field = False is_FiniteField = is_FF = False is_IntegerRing = is_ZZ = False is_RationalField = is_QQ = False is_RealField = is_RR = False is_ComplexField = is_CC = False is_AlgebraicField = is_Algebraic = False is_RealAlgebraicField = False is_ComplexAlgebraicField = False is_PolynomialRing = is_Poly = False is_FractionField = is_Frac = False is_SymbolicDomain = is_EX = False is_Exact = True is_Numerical = False is_Simple = False is_Composite = False rep = None def __hash__(self): return hash((self.__class__.__name__, self.dtype)) def __call__(self, *args): """Construct an element of ``self`` domain from ``args``. """ return self.dtype(*args)
[docs] @abc.abstractmethod def from_expr(self, element): """Convert Diofant's expression to ``dtype``. """ raise NotImplementedError
[docs] @abc.abstractmethod def to_expr(self, element): """Convert ``element`` to Diofant expression. """ raise NotImplementedError
[docs] def convert_from(self, element, base): """Convert ``element`` to ``self.dtype`` given the base domain. """ for superclass in inspect.getmro(base.__class__): method = "_from_" + superclass.__name__ convert = getattr(self, method, None) if convert: result = convert(element, base) if result is not None: return result raise CoercionFailed("can't convert %s of type %s from %s " "to %s" % (element, type(element), base, self))
[docs] def convert(self, element, base=None): """Convert ``element`` to ``self.dtype``. """ if base is not None: return self.convert_from(element, base) if isinstance(element, self.dtype): return element from .integerring import PythonIntegerRing, GMPYIntegerRing from .rationalfield import PythonRationalField, GMPYRationalField from . import RealField, ComplexField, PythonRational if isinstance(element, int): return self.convert_from(element, PythonIntegerRing()) if isinstance(element, PythonRational): return self.convert_from(element, PythonRationalField()) if HAS_GMPY: integers = GMPYIntegerRing() if isinstance(element, integers.dtype): return self.convert_from(element, integers) rationals = GMPYRationalField() if isinstance(element, rationals.dtype): return self.convert_from(element, rationals) if isinstance(element, float): parent = RealField(tol=False) return self.convert_from(parent(element), parent) if isinstance(element, complex): parent = ComplexField(tol=False) return self.convert_from(parent(element), parent) if isinstance(element, DomainElement): return self.convert_from(element, element.parent) if isinstance(element, Expr): try: return self.from_expr(element) except (TypeError, ValueError): pass raise CoercionFailed("can't convert %s of type %s to %s" % (element, type(element), self))
def __contains__(self, a): """Check if ``a`` belongs to this domain. """ try: self.convert(a) return True except CoercionFailed: return False def _from_PolynomialRing(self, a, K0): if a.is_ground: return self.convert(a.LC, K0.domain)
[docs] def unify(self, K1, symbols=()): """ Construct a minimal domain that contains elements of ``self`` and ``K1``. Known domains (from smallest to largest): - ``GF(p)`` - ``ZZ`` - ``QQ`` - ``RR(prec, tol)`` - ``CC(prec, tol)`` - ``ALG(a, b, c)`` - ``K[x, y, z]`` - ``K(x, y, z)`` - ``EX`` """ if symbols: if any(d.is_Composite and (set(d.symbols) & set(symbols)) for d in [self, K1]): raise UnificationFailed("Can't unify %s with %s, given %s" " generators" % (self, K1, tuple(symbols))) return self.unify(K1) if self == K1: return self if self.is_SymbolicDomain: return self if K1.is_SymbolicDomain: return K1 if self.is_Composite or K1.is_Composite: self_ground = self.domain if self.is_Composite else self K1_ground = K1.domain if K1.is_Composite else K1 self_symbols = self.symbols if self.is_Composite else () K1_symbols = K1.symbols if K1.is_Composite else () domain = self_ground.unify(K1_ground) symbols = _unify_gens(self_symbols, K1_symbols) order = self.order if self.is_Composite else K1.order if ((self.is_FractionField and K1.is_PolynomialRing or K1.is_FractionField and self.is_PolynomialRing) and (not self_ground.is_Field or not K1_ground.is_Field) and domain.has_assoc_Ring): domain = domain.ring if self.is_Composite and (not K1.is_Composite or self.is_FractionField or K1.is_PolynomialRing): cls = self.__class__ else: cls = K1.__class__ return cls(domain, symbols, order) def mkinexact(cls, K0, K1): prec = max(K0.precision, K1.precision) tol = max(K0.tolerance, K1.tolerance) return cls(prec=prec, tol=tol) if self.is_ComplexField and K1.is_ComplexField: return mkinexact(self.__class__, self, K1) if self.is_ComplexField and K1.is_RealField: return mkinexact(self.__class__, self, K1) if self.is_RealField and K1.is_ComplexField: return mkinexact(K1.__class__, K1, self) if self.is_RealField and K1.is_RealField: return mkinexact(self.__class__, self, K1) if self.is_ComplexField or self.is_RealField: return self if K1.is_ComplexField or K1.is_RealField: return K1 if self.is_AlgebraicField and K1.is_AlgebraicField: return self.__class__(self.domain.unify(K1.domain), *_unify_gens(self.gens, K1.gens)) elif self.is_AlgebraicField: return self elif K1.is_AlgebraicField: return K1 if self.is_RationalField: return self if K1.is_RationalField: return K1 if self.is_FiniteField and self.domain == K1: return self if K1.is_FiniteField and K1.domain == self: return K1 raise NotImplementedError
def __eq__(self, other): """Returns ``True`` if two domains are equivalent. """ return isinstance(other, Domain) and self.dtype == other.dtype
[docs] def get_exact(self): """Returns an exact domain associated with ``self``. """ return self
[docs] def poly_ring(self, *symbols, **kwargs): """Returns a polynomial ring, i.e. `K[X]`. """ from ..polys import PolynomialRing return PolynomialRing(self, symbols, kwargs.get("order", lex))
[docs] def frac_field(self, *symbols, **kwargs): """Returns a fraction field, i.e. `K(X)`. """ from ..polys import FractionField return FractionField(self, symbols, kwargs.get("order", lex))
[docs] def is_positive(self, a): """Returns True if ``a`` is positive. """ return a > 0
[docs] def is_negative(self, a): """Returns True if ``a`` is negative. """ return a < 0