On 16 April 2018 at 00:06, Nils Bruin <nbr...@sfu.ca> wrote: > On Sunday, April 15, 2018 at 3:53:08 PM UTC-7, Dima Pasechnik wrote: >> >> >> It would be nice to have better simplification rules for QQ (and more >>> generally fraction fields). >>> >> >> I suppose it's only OK to have as an option, as in general computing such >> a canonical >> form would be slow, no? >> >> For fraction fields of euclidean domains it's not so bad (as > ZZ['x'].fraction_field() shows). Furthermore, if you consistently don't > clear common content from your numerator/denominator pairs you can end up > with quite bad coefficient blow-up. > > Of course, the work-around is to use Z['x'].fraction_field(). >

In this case (one variable, over QQ) it would be simple to extract the leading coefficients of the numerator and denominator, say a and b, reduce the rational number a/b to a1/b1, and scale the rational function so that the new leading coefficients are a1 and b1 which will be coprime integers. This is simpler than writing numerator and denominator as a rational times a primitive integral polynomial, though that is probably what users would prefer. John > -- > 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 post to this group, send email to sage-devel@googlegroups.com. > Visit this group at https://groups.google.com/group/sage-devel. > For more options, visit https://groups.google.com/d/optout. > -- 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 post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.