I suspect this is just an oversight in the R.number_field() method -- for instance, the following causes trouble:
sage: A.<x> = QQ[] sage: R = A.quotient_ring(x^2+x+1) sage: K = R.number_field() sage: K Number Field in xbar with defining polynomial x^2 + x + 1 sage: x.parent() Univariate Polynomial Ring in x over Rational Field sage: K(x) xbar sage: R(x) xbar sage: K(R(x)) ------------------------------------------------------------------------ --- <type 'exceptions.TypeError'> Traceback (most recent call last) /Users/craigcitro/<ipython console> in <module>() /sage/local/lib/python2.5/site-packages/sage/rings/number_field/ number_field. in __call__(self, x) 1033 elif isinstance(x,str): 1034 return self._coerce_from_str(x) -> 1035 return self._coerce_non_number_field_element_in(x) 1036 1037 def _coerce_from_str(self, x): /sage/local/lib/python2.5/site-packages/sage/rings/number_field/ number_field. in _coerce_non_number_field_element_in(self, x) 1123 except (TypeError, AttributeError), msg: 1124 pass -> 1125 raise TypeError 1126 1127 def _coerce_impl(self, x): <type 'exceptions.TypeError'>: That is, if R is my PolynomialQuotientRing, and K is the associated number field, I can't coerce from R to K! Even K(R(1)) fails. Maybe this one is just me misunderstanding the coercion model, because you can pretty easily make it work: sage: H = Hom(R,K) sage: H Set of Homomorphisms from Univariate Quotient Polynomial Ring in xbar over Rational Field with modulus x^2 + x + 1 to Number Field in xbar with defining polynomial x^2 + x + 1 sage: K.0 xbar sage: H(([K.0])) Ring morphism: From: Univariate Quotient Polynomial Ring in xbar over Rational Field with modulus x^2 + x + 1 To: Number Field in xbar with defining polynomial x^2 + x + 1 Defn: xbar |--> xbar sage: f = H(([K.0])) sage: f(R(1)) 1 sage: f(R(x)) xbar However, I haven't played with what David Roe was pointing out to see how that goes; presumably that problem is still present. -cc --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
