I think this is a good idea. -M. Hampton
On May 15, 8:20 am, Jason Grout <[EMAIL PROTECTED]> wrote: > Based on some conversations with linear algebra people and classroom > demonstrations in a linear algebra class, people are confused that when > they create a matrix with matrix(3, range(9)), for example, that the > echelon_form is not the rref output that they get from most any other > program they have ever used, and certainly not what is taught in an > undergrad linear algebra class. There is additional confusion if the > entries specified have a fraction in them; then the matrix defaults to > being over QQ, and the echelon_form functino gives the expected naive > rref! The problem, of course, lies in the matrix defaulting to having > base_ring == ZZ (i.e., non-field). > > What do people think about making the default ring for matrices QQ? > Additionally, if the ring R is determined from the elements provided, > then the matrix would be over R.fraction_field(). Of course, the > documentation for matrix() would clearly indicate what is happening if > the ring is not specified. > > With this change: > > matrix(3, range(9)) would yield a matrix over QQ because the elements > live in ZZ, and then we call ZZ.fraction_field() to get the base ring of > the matrix. > > matrix(3,3) would yield a matrix over QQ because QQ would be the default > ring if no entries are specified. > > matrix(R,...) would yield a ring over R, since R was explicitly specified. > > 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 -~----------~----~----~----~------~----~------~--~---
