2007/7/30, Carl Witty <[EMAIL PROTECTED]>: > It seems pretty strange to me, mostly because you lose too much > information by eliding zeroes. As far as I can tell, given > MPolynomialRing(QQ,2,order='lex'), all of the following polynomials: > > 3*x^2 + 1 > 3*x^5 + x > 3*y^7 + 1 > 3*y + 1 > > would have a coefficients() list of [3, 1]. Is that true, and if so, > is this really a useful function?
For me it makes sense because I just need a method that iterates over the coefficients of a polynomial. Having the ordering respected is a little extra that I think helps the user. I could put the zeros in there, but her are my own subjective reasons not to: - I think of multivariate polynomials as sparse polynomials, so I think coefficients() with the 0s omitted is OK. - Maple does the same thing :) (I know, I know: not an argument...) - Putting these zeros involves generating all the degree exponents, which is slower. It can be done, but generating all the coefficients this way for something like f = x^6*y^12*z^2 makes a big list made mostly of zeros. Here's a compromise: a paramater, (say all_coefficients) could be specified to have an explicit list. Thoughts? didier --~--~---------~--~----~------------~-------~--~----~ 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://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
