Merge #32612

src/sage/dynamics/arithmetic_dynamics/projective_ds.py

@@ -80,16 +80,15 @@ class initialization directly.
 from sage.rings.polynomial.flatten import FlatteningMorphism, UnflatteningMorphism
 from sage.rings.morphism import RingHomomorphism_im_gens
 from sage.rings.number_field.number_field_ideal import NumberFieldFractionalIdeal
-from sage.rings.number_field.number_field import is_NumberField
 from sage.rings.padics.all import Qp
 from sage.rings.polynomial.multi_polynomial_ring_base import is_MPolynomialRing
 from sage.rings.polynomial.polynomial_ring_constructor import PolynomialRing
 from sage.rings.polynomial.polynomial_ring import is_PolynomialRing
 from sage.rings.qqbar import QQbar, number_field_elements_from_algebraics
 from sage.rings.quotient_ring import QuotientRing_generic
 from sage.rings.rational_field import QQ
-from sage.rings.real_double import RDF
-from sage.rings.real_mpfr import (RealField, is_RealField)
+import sage.rings.abc
+from sage.rings.real_mpfr import RealField
 from sage.schemes.generic.morphism import SchemeMorphism_polynomial
 from sage.schemes.projective.projective_subscheme import AlgebraicScheme_subscheme_projective
 from sage.schemes.projective.projective_morphism import (
@@ -2062,10 +2061,10 @@ def canonical_height(self, P, **kwds):
 
         # Archimedean local heights
         # :: WARNING: If places is fed the default Sage precision of 53 bits,
-        # it uses Real or Complex Double Field in place of RealField(prec) or ComplexField(prec)
-        # the function is_RealField does not identify RDF as real, so we test for that ourselves.
+        # it uses Real or Complex Double Field in place of RealField(prec) or ComplexField(prec).
+        # RDF is an instance of a separate class.
         for v in emb:
-            if is_RealField(v.codomain()) or v.codomain() is RDF:
+            if isinstance(v.codomain(), (sage.rings.abc.RealField, sage.rings.abc.RealDoubleField)):
                 dv = R.one()
             else:
                 dv = R(2)

src/sage/functions/orthogonal_polys.py

@@ -304,8 +304,7 @@
 from sage.misc.latex import latex
 from sage.rings.all import ZZ, QQ, RR, CC
 from sage.rings.polynomial.polynomial_ring_constructor import PolynomialRing
-from sage.rings.real_mpfr import is_RealField
-from sage.rings.complex_mpfr import is_ComplexField
+import sage.rings.abc
 
 from sage.symbolic.function import BuiltinFunction, GinacFunction
 from sage.symbolic.expression import Expression
@@ -672,7 +671,7 @@ def _evalf_(self, n, x, **kwds):
         except KeyError:
             real_parent = parent(x)
 
-            if not is_RealField(real_parent) and not is_ComplexField(real_parent):
+            if not isinstance(real_parent, (sage.rings.abc.RealField, sage.rings.abc.ComplexField)):
                 # parent is not a real or complex field: figure out a good parent
                 if x in RR:
                     x = RR(x)
@@ -681,7 +680,7 @@ def _evalf_(self, n, x, **kwds):
                     x = CC(x)
                     real_parent = CC
 
-        if not is_RealField(real_parent) and not is_ComplexField(real_parent):
+        if not isinstance(real_parent, (sage.rings.abc.RealField, sage.rings.abc.ComplexField)):
             raise TypeError("cannot evaluate chebyshev_T with parent {}".format(real_parent))
 
         from sage.libs.mpmath.all import call as mpcall
@@ -1031,7 +1030,7 @@ def _evalf_(self, n, x, **kwds):
         except KeyError:
             real_parent = parent(x)
 
-            if not is_RealField(real_parent) and not is_ComplexField(real_parent):
+            if not isinstance(real_parent, (sage.rings.abc.RealField, sage.rings.abc.ComplexField)):
                 # parent is not a real or complex field: figure out a good parent
                 if x in RR:
                     x = RR(x)
@@ -1040,7 +1039,7 @@ def _evalf_(self, n, x, **kwds):
                     x = CC(x)
                     real_parent = CC
 
-        if not is_RealField(real_parent) and not is_ComplexField(real_parent):
+        if not isinstance(real_parent, (sage.rings.abc.RealField, sage.rings.abc.ComplexField)):
             raise TypeError("cannot evaluate chebyshev_U with parent {}".format(real_parent))
 
         from sage.libs.mpmath.all import call as mpcall

src/sage/functions/special.py

@@ -158,8 +158,8 @@
 #                  https://www.gnu.org/licenses/
 # ****************************************************************************
 
+import sage.rings.abc
 from sage.rings.integer import Integer
-from sage.rings.complex_mpfr import ComplexField
 from sage.misc.latex import latex
 from sage.rings.all import ZZ
 from sage.symbolic.constants import pi
@@ -362,10 +362,9 @@ def elliptic_j(z, prec=53):
         sage: (-elliptic_j(tau, 100).real().round())^(1/3)
         640320
     """
-
     CC = z.parent()
-    from sage.rings.complex_mpfr import is_ComplexField
-    if not is_ComplexField(CC):
+    if not isinstance(CC, sage.rings.abc.ComplexField):
+        from sage.rings.complex_mpfr import ComplexField
         CC = ComplexField(prec)
         try:
             z = CC(z)

src/sage/matrix/misc.pyx

@@ -40,7 +40,7 @@ from sage.rings.rational_field import QQ
 from sage.rings.integer cimport Integer
 from sage.arith.all import previous_prime, CRT_basis
 
-from sage.rings.real_mpfr import  is_RealField
+from sage.rings.real_mpfr cimport RealField_class
 from sage.rings.real_mpfr cimport RealNumber
 
 
@@ -510,7 +510,7 @@ def hadamard_row_bound_mpfr(Matrix A):
         ...
         OverflowError: cannot convert float infinity to integer
     """
-    if not is_RealField(A.base_ring()):
+    if not isinstance(A.base_ring(), RealField_class):
         raise TypeError("A must have base field an mpfr real field.")
 
     cdef RealNumber a, b

src/sage/modular/dirichlet.py

@@ -68,7 +68,7 @@
 
 from sage.categories.map import Map
 from sage.rings.rational_field import is_RationalField
-from sage.rings.complex_mpfr import is_ComplexField
+import sage.rings.abc
 from sage.rings.qqbar import is_AlgebraicField
 from sage.rings.ring import is_Ring
 
@@ -1153,7 +1153,7 @@ def _pari_init_(self):
 
         # now compute the input for pari (list of exponents)
         P = self.parent()
-        if is_ComplexField(P.base_ring()):
+        if isinstance(P.base_ring(), sage.rings.abc.ComplexField):
             zeta = P.zeta()
             zeta_argument = zeta.argument()
             v = [int(x.argument() / zeta_argument) for x in values_on_gens]
@@ -1345,7 +1345,7 @@ def gauss_sum(self, a=1):
         K = G.base_ring()
         chi = self
         m = G.modulus()
-        if is_ComplexField(K):
+        if isinstance(K, sage.rings.abc.ComplexField):
             return self.gauss_sum_numerical(a=a)
         elif is_AlgebraicField(K):
             L = K
@@ -1422,7 +1422,7 @@ def gauss_sum_numerical(self, prec=53, a=1):
         """
         G = self.parent()
         K = G.base_ring()
-        if is_ComplexField(K):
+        if isinstance(K, sage.rings.abc.ComplexField):
 
             def phi(t):
                 return t
@@ -2138,7 +2138,7 @@ def element(self):
         """
         P = self.parent()
         M = P._module
-        if is_ComplexField(P.base_ring()):
+        if isinstance(P.base_ring(), sage.rings.abc.ComplexField):
             zeta = P.zeta()
             zeta_argument = zeta.argument()
             v = M([int(round(x.argument() / zeta_argument))
@@ -2607,7 +2607,7 @@ def _zeta_powers(self):
         w = [a]
         zeta = self.zeta()
         zeta_order = self.zeta_order()
-        if is_ComplexField(R):
+        if isinstance(R, sage.rings.abc.ComplexField):
             for i in range(1, zeta_order):
                 a = a * zeta
                 a._set_multiplicative_order(zeta_order / gcd(zeta_order, i))

src/sage/modules/free_module.py

@@ -170,6 +170,7 @@
 from sage.modules.module import Module
 import sage.rings.finite_rings.finite_field_constructor as finite_field
 import sage.rings.ring as ring
+import sage.rings.abc
 import sage.rings.integer_ring
 import sage.rings.rational_field
 import sage.rings.abc
@@ -7443,9 +7444,9 @@ def element_class(R, is_sparse):
             return Vector_modn_dense
         else:
             return free_module_element.FreeModuleElement_generic_dense
-    elif sage.rings.real_double.is_RealDoubleField(R) and not is_sparse:
+    elif isinstance(R, sage.rings.abc.RealDoubleField) and not is_sparse:
         return sage.modules.vector_real_double_dense.Vector_real_double_dense
-    elif sage.rings.complex_double.is_ComplexDoubleField(R) and not is_sparse:
+    elif isinstance(R, sage.rings.abc.ComplexDoubleField) and not is_sparse:
         return sage.modules.vector_complex_double_dense.Vector_complex_double_dense
     elif sage.symbolic.ring.is_SymbolicExpressionRing(R) and not is_sparse:
         import sage.modules.vector_symbolic_dense

src/sage/probability/random_variable.py

@@ -15,10 +15,10 @@
 #                  https://www.gnu.org/licenses/
 # ****************************************************************************
 
+import sage.rings.abc
 from sage.structure.parent import Parent
 from sage.functions.log import log
 from sage.functions.all import sqrt
-from sage.rings.real_mpfr import (RealField, is_RealField)
 from sage.rings.rational_field import is_RationalField
 from sage.sets.set import Set
 from pprint import pformat
@@ -83,6 +83,7 @@ def __init__(self, X, f, codomain=None, check=False):
         if check:
             raise NotImplementedError("Not implemented")
         if codomain is None:
+            from sage.rings.real_mpfr import RealField
             RR = RealField()
         else:
             RR = codomain
@@ -337,8 +338,9 @@ def __init__(self, X, P, codomain=None, check=False):
             1.50000000000000
         """
         if codomain is None:
+            from sage.rings.real_mpfr import RealField
             codomain = RealField()
-        if not is_RealField(codomain) and not is_RationalField(codomain):
+        if not isinstance(codomain, sage.rings.abc.RealField) and not is_RationalField(codomain):
             raise TypeError("Argument codomain (= %s) must be the reals or rationals" % codomain)
         if check:
             one = sum(P.values())

src/sage/quadratic_forms/special_values.py

@@ -9,13 +9,12 @@
 
 from sage.combinat.combinat import bernoulli_polynomial
 from sage.misc.functional import denominator
-from sage.rings.all import RealField
 from sage.arith.all import kronecker_symbol, bernoulli, factorial, fundamental_discriminant
 from sage.rings.infinity import infinity
 from sage.rings.integer_ring import ZZ
 from sage.rings.polynomial.polynomial_ring_constructor import PolynomialRing
 from sage.rings.rational_field import QQ
-from sage.rings.real_mpfr import is_RealField
+import sage.rings.abc
 from sage.symbolic.constants import pi, I
 
 # ---------------- The Gamma Function  ------------------
@@ -278,9 +277,10 @@ def quadratic_L_function__numerical(n, d, num_terms=1000):
         ....:         print("Oops! We have a problem at d = {}: exact = {}, numerical = {}".format(d, RR(quadratic_L_function__exact(1, d)), RR(quadratic_L_function__numerical(1, d))))
     """
     # Set the correct precision if it is given (for n).
-    if is_RealField(n.parent()):
+    if isinstance(n.parent(), sage.rings.abc.RealField):
         R = n.parent()
     else:
+        from sage.rings.real_mpfr import RealField
         R = RealField()
 
     if n < 0:

src/sage/rings/abc.pxd

@@ -5,6 +5,11 @@ cdef class RealField(Field):
     pass
 
 
+cdef class RealIntervalField(Field):
+
+    pass
+
+
 cdef class RealDoubleField(Field):
 
     pass

src/sage/rings/abc.pyx

@@ -10,6 +10,22 @@ cdef class RealField(Field):
     pass
 
 
+class RealBallField(Field):
+    r"""
+    Abstract base class for :class:`~sage.rings.real_arb.RealBallField`.
+    """
+
+    pass
+
+
+cdef class RealIntervalField(Field):
+    r"""
+    Abstract base class for :class:`~sage.rings.real_mpfi.RealIntervalField_class`.
+    """
+
+    pass
+
+
 cdef class RealDoubleField(Field):
     r"""
     Abstract base class for :class:`~sage.rings.real_double.RealDoubleField_class`.
@@ -26,6 +42,22 @@ cdef class ComplexField(Field):
     pass
 
 
+class ComplexBallField(Field):
+    r"""
+    Abstract base class for :class:`~sage.rings.complex_arb.ComplexBallField`.
+    """
+
+    pass
+
+
+class ComplexIntervalField(Field):
+    r"""
+    Abstract base class for :class:`~sage.rings.complex_interval_field.ComplexIntervalField_class`.
+    """
+
+    pass
+
+
 cdef class ComplexDoubleField(Field):
     r"""
     Abstract base class for :class:`~sage.rings.complex_double.ComplexDoubleField_class`.

src/sage/rings/complex_arb.pyx

@@ -147,6 +147,7 @@ from cysignals.signals cimport sig_on, sig_str, sig_off, sig_error
 
 import sage.categories.fields
 
+cimport sage.rings.abc
 cimport sage.rings.rational
 
 from cpython.float cimport PyFloat_AS_DOUBLE
@@ -301,7 +302,8 @@ cdef int acb_calc_func_callback(acb_ptr out, const acb_t inp, void * param,
     finally:
         sig_on()
 
-class ComplexBallField(UniqueRepresentation, Field):
+
+class ComplexBallField(UniqueRepresentation, sage.rings.abc.ComplexBallField):
     r"""
     An approximation of the field of complex numbers using pairs of mid-rad
     intervals.

src/sage/rings/complex_double.pyx

@@ -111,18 +111,28 @@ from sage.structure.richcmp cimport rich_to_bool
 cimport gmpy2
 gmpy2.import_gmpy2()
 
+
 def is_ComplexDoubleField(x):
     """
     Return ``True`` if ``x`` is the complex double field.
 
+    This function is deprecated. Use :func:`isinstance` with
+    :class:`~sage.rings.abc.ComplexDoubleField` instead.
+
     EXAMPLES::
 
         sage: from sage.rings.complex_double import is_ComplexDoubleField
         sage: is_ComplexDoubleField(CDF)
+        doctest:warning...
+        DeprecationWarning: is_ComplexDoubleField is deprecated;
+        use isinstance(..., sage.rings.abc.ComplexDoubleField) instead
+        See https://trac.sagemath.org/32610 for details.
         True
         sage: is_ComplexDoubleField(ComplexField(53))
         False
     """
+    from sage.misc.superseded import deprecation
+    deprecation(32610, 'is_ComplexDoubleField is deprecated; use isinstance(..., sage.rings.abc.ComplexDoubleField) instead')
     return isinstance(x, ComplexDoubleField_class)
 
 

src/sage/rings/complex_interval_field.py

@@ -40,6 +40,7 @@
 from .integer_ring import ZZ
 from .rational_field import QQ
 from .ring import Field
+import sage.rings.abc
 from . import integer
 from . import complex_interval
 import weakref
@@ -56,12 +57,19 @@ def is_ComplexIntervalField(x):
 
         sage: from sage.rings.complex_interval_field import is_ComplexIntervalField as is_CIF
         sage: is_CIF(CIF)
+        doctest:warning...
+        DeprecationWarning: is_ComplexIntervalField is deprecated;
+        use isinstance(..., sage.rings.abc.ComplexIntervalField) instead
+        See https://trac.sagemath.org/32612 for details.
         True
         sage: is_CIF(CC)
         False
     """
+    from sage.misc.superseded import deprecation
+    deprecation(32612, 'is_ComplexIntervalField is deprecated; use isinstance(..., sage.rings.abc.ComplexIntervalField) instead')
     return isinstance(x, ComplexIntervalField_class)
 
+
 cache = {}
 def ComplexIntervalField(prec=53, names=None):
     """
@@ -93,7 +101,7 @@ def ComplexIntervalField(prec=53, names=None):
     return C
 
 
-class ComplexIntervalField_class(Field):
+class ComplexIntervalField_class(sage.rings.abc.ComplexIntervalField):
     """
     The field of complex (interval) numbers.