-1. While I agree that defaulting to matrices over QQ rather than over ZZ would lead to more expected behaviour for most users, I don't see how the rule for changing the base ring can be made both consistent and cheap.
Imagine R1 = QQ[x,y]/(x^2+y^2-1). Then FieldOfFractions(R1) is well- defined, so one would expect that matrix([x]) would be over the field of fractions. If R2=Q[x,y]/( x^2-y^2), FieldOfFractions(R2) does not exist. Deciding whether FieldOfFractions(Ri) exists is a fairly expensive operation in these cases. I think special-casing matrix([ZZ(1)]) etc. is a bad idea. You would need a method R.has_an_obvious_field_of_fractions() on rings to both deal with ZZ and avoid expensive operations for R1 and R2 above. --~--~---------~--~----~------------~-------~--~----~ 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://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
