The situation is as follows: sage: R.<a, b> = ZZ[] sage: (2*a/b).factor() 2 * b^-1 * a sage: (a/(2*b)).factor() 2^-1 * b^-1 * a sage: (3*a/(2*b)).factor() Traceback (most recent call last): ... TypeError: Cannot multiply 3 * a and 2^-1 * b^-1 because they cannot be coerced into a common universe
However, the univariate ring behaves differently: sage: S.<c> = ZZ[] sage: (2*c/(c+1)).factor() 2 * (c + 1)^-1 * c sage: (c/(2*(c+1))).factor() 2^-1 * (c + 1)^-1 * c sage: (3*c/(2*(c+1))).factor() 2^-1 * 3 * (c + 1)^-1 * c Am 2017-02-16 um 17:11 schrieb John Cremona: > On 16 February 2017 at 15:07, Clemens Heuberger > I would say that was a bug. Change ZZ to QQ and it is fine. I still consider the current behaviour to be a bug, especially in view of the better behaviour of the univariate ring. In particular, throwing a TypeError seems to be quite inappropriate here. I usually prefer to work in the fraction field of ZZ[] because the results tend to be nicer (and I am not particularly happy to convert my final result just to get some copy&paste ready version). -- 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.
