Jason Grout wrote: > In the recent discussion "Change the default base_ring for matrices from > ZZ to QQ", there were lots of opinions shared, and William summarized > some feelings from the group, but it wasn't a solid conclusion (at > least, based on an IRC conversation, William is rethinking the conclusion). > > Here are two (somewhat competing) proposals, one from an IRC discussion > with William just now and the other from William's summary from the > previous thread. > > Proposal A: > > If a ring is not specified in a matrix() call, and the elements provided > are all integers (or if there are no elements provided), then the base > ring would default to QQ (instead of ZZ, as would currently happen). > > Reasons (from William and from discussions with a linear algebra person): > > 1. "linear algebra" is over fields (as opposed to module theory). When > commonly-created matrices (i.e., ones with integer entries or with no > specified entries) "default" to non-fields, the behavior is very > surprising to linear algebra people and casual users (like linear > algebra students, for example). > > 2. the matrix() command was designed for ease of use for "casual end users" > > 3. It is very easy to explicitly specify a ring, either in matrix() or > via MatrixSpace > > > So here are the cases we would see a change in behavior > > matrix(3,3) would return a 3x3 zero matrix over QQ instead of over ZZ > > matrix(3,range(9)) would return a 3x3 matrix over QQ instead of over ZZ. > > > Proposal B (from William's summary on the previous thread): > > Leave matrix() as-is. Rename echelon_form to hermite_form, and make a > new echelon_form function that computes hermite_form over the fraction > field of the base ring.
It sounds like the popular vote selects proposal B. This is being tracked at #3211. Thanks, Jason --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
