Ah, thank you! On Wednesday, 12 October 2022 at 23:19:09 UTC+2 David Roe wrote:
> It's the difference between conversion and coercion. > > P = PolynomialRing(GF(2), "z", sparse=True); Q = PolynomialRing(ZZ, "z", > sparse=False) > sage: P.convert_map_from(Q) > Conversion map: > From: Univariate Polynomial Ring in z over Integer Ring > To: Sparse Univariate Polynomial Ring in z over Finite Field of size 2 > sage: P.convert_map_from(Q)(Q.gen()) > z > > David > > On Wed, Oct 12, 2022 at 5:15 PM 'Martin R' via sage-devel < > sage-...@googlegroups.com> wrote: > >> Sorry, I don't understand your last sentence. We have >> >> sage: P = PolynomialRing(GF(2), "z", sparse=True); Q = >> PolynomialRing(ZZ, "z", sparse=False) >> sage: P.has_coerce_map_from(Q) >> False >> >> How does this fit with >> >> "And of course you can convert even when Q is not sparse."? >> >> Martin >> >> On Wednesday, 12 October 2022 at 23:04:38 UTC+2 David Roe wrote: >> >>> Yes, that's expected. >>> >>> sage: P = PolynomialRing(GF(2), "z", sparse=True); Q = >>> PolynomialRing(ZZ, "z", sparse=True) >>> sage: P.has_coerce_map_from(Q) >>> True >>> >>> And of course you can convert even when Q is not sparse. >>> David >>> >>> On Wed, Oct 12, 2022 at 4:58 PM 'Martin R' via sage-devel < >>> sage-...@googlegroups.com> wrote: >>> >>>> I have no idea whether the following is to be expected: >>>> >>>> sage: P = PolynomialRing(GF(2), "z", sparse=False); Q = >>>> PolynomialRing(ZZ, "z") >>>> sage: P.has_coerce_map_from(Q) >>>> True >>>> >>>> sage: P = PolynomialRing(GF(2), "z", sparse=True); Q = >>>> PolynomialRing(ZZ, "z") >>>> sage: P.has_coerce_map_from(Q) >>>> False >>>> >>>> Martin >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "sage-devel" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to sage-devel+...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/sage-devel/c585103b-9dfa-4e25-b36b-20f8fb937435n%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/sage-devel/c585103b-9dfa-4e25-b36b-20f8fb937435n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- >> You received this message because you are subscribed to the Google Groups >> "sage-devel" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to sage-devel+...@googlegroups.com. >> > To view this discussion on the web visit >> https://groups.google.com/d/msgid/sage-devel/5d443b30-3171-4a6c-bfdc-c61100680cc9n%40googlegroups.com >> >> <https://groups.google.com/d/msgid/sage-devel/5d443b30-3171-4a6c-bfdc-c61100680cc9n%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-devel/3f51dc5d-09fc-4809-b908-eec488d661e9n%40googlegroups.com.
