Polyring_FpT_coerce cannot handle polynomial_modn_dense_ntl #15954
Description
sage: R.<x> = PolynomialRing(Integers(101), implementation='NTL')
sage: 1/x
---------------------------------------------------------------------------
NotImplementedError Traceback (most recent call last)
<ipython-input-2-3e814ccafd34> in <module>()
----> 1 Integer(1)/x
/usr/local/src/sage-config/src/sage/rings/integer.pyx in sage.rings.integer.Integer.__div__ (build/cythonized/sage/rings/integer.c:13187)()
1874 return y
1875
-> 1876 return coercion_model.bin_op(left, right, operator.div)
1877
1878 cpdef _div_(self, right):
/usr/local/src/sage-config/src/sage/structure/coerce.pyx in sage.structure.coerce.CoercionModel_cache_maps.bin_op (build/cythonized/sage/structure/coerce.c:9515)()
1079 try:
1080 xy = self.canonical_coercion(x,y)
-> 1081 return PyObject_CallObject(op, xy)
1082 except TypeError as err:
1083 if xy is not None:
/usr/local/src/sage-config/src/sage/rings/polynomial/polynomial_element.pyx in sage.rings.polynomial.polynomial_element.Polynomial.__div__ (build/cythonized/sage/rings/polynomial/polynomial_element.c:23976)()
2121
2122 def __div__(left, right):
-> 2123 return PyNumber_TrueDivide(left, right)
2124
2125 def __pow__(left, right, modulus):
/usr/local/src/sage-config/src/sage/rings/polynomial/polynomial_element.pyx in sage.rings.polynomial.polynomial_element.Polynomial.__truediv__ (build/cythonized/sage/rings/polynomial/polynomial_element.c:23681)()
2103 # Same parents => bypass coercion
2104 if have_same_parent(left, right):
-> 2105 return (<Element>left)._div_(right)
2106
2107 # Try division of polynomial by a scalar
/usr/local/src/sage-config/src/sage/structure/element.pyx in sage.structure.element.RingElement._div_ (build/cythonized/sage/structure/element.c:17628)()
2476 except AttributeError:
2477 raise bin_op_exception('/', self, other)
-> 2478 return frac(self, other)
2479
2480 def __invert__(self):
/usr/local/src/sage-config/src/sage/structure/parent.pyx in sage.structure.parent.Parent.__call__ (build/cythonized/sage/structure/parent.c:9433)()
917 return mor._call_(x)
918 else:
--> 919 return mor._call_with_args(x, args, kwds)
920
921 raise TypeError("No conversion defined from %s to %s"%(R, self))
/usr/local/src/sage-config/src/sage/rings/fraction_field_FpT.pyx in sage.rings.fraction_field_FpT.Polyring_FpT_coerce._call_with_args (build/cythonized/sage/rings/fraction_field_FpT.cpp:12573)()
1132 x = <Polynomial_zmod_flint?> _x
1133 except TypeError:
-> 1134 raise NotImplementedError('Fraction fields not implemented for this type.')
1135 cdef FpTElement ans = <FpTElement>FpTElement.__new__(FpTElement)
1136 ans._parent = self.codomain()
NotImplementedError: Fraction fields not implemented for this type.
This makes NTL modpolys unusable in fractions.
Component: coercion
Author: Ralf Stephan
Branch/Commit: u/rws/polyring_fpt_coerce_cannot_handle_polynomial_modn_dense_ntl @ ded2b6d
Reviewer: Karl-Dieter Crisman
Issue created by migration from https://trac.sagemath.org/ticket/15954