My first guess for #9046 is that the problem is located within the last line of collect : return x + (*this-x).expand(); In that case (*this-x).expand() should be zero but looks like: -x^2 - 2*y^3 - y^2*z + x^2 + 2*y^3 + y^2*z I think that whithin the call to expand(), expairseq::combine_same_terms_sorted_seq() is called after canonicalize(); but with the new order x^2 and -x^2, etc. are not adjacent and do not get simplified... whence the above expression for (*this-x).expand() and finally for p.collect(x). I'll look at the ordering problem causing that tomorrow.
On 29 sep, 18:48, Jean-Pierre Flori <[email protected]> wrote: > Hi, > > Maybe it is a good thing to keep the same order as ginac internally > and your more usual ordering for printing. > However if you'd better not duplicate code, I can look at the "- > x^2+x^2" part of bug #9046. > Now I may understand a big enough part of pynac code to do that. > But if you'd better use the above patch, that won't be necessary. > > Cheers, > > On 29 sep, 17:33, Burcin Erocal <[email protected]> wrote: > > > Hi, > > > On Wed, 29 Sep 2010 07:00:39 -0700 (PDT) > > > Jean-Pierre Flori <[email protected]> wrote: > > > Ok, I have finally looked at the comparison functions and exchanging : > > > cmpval = seq[0].coeff.compare(other.exponent); > > > by > > > cmpval = -seq[0].coeff.compare(other.exponent); > > > in mul::compare_pow (mul.cpp:1265) seems to prevent the above bug from > > > happening. > > > It seems to fit better with the change made by William Stein in > > > power::compare_same_type (power.cpp:951). > > > However it doesn't mean the problem is completely solved... > > > I'll try to take a deeper look at the comparison functions at some > > > point. > > > Thank you for following up on this and taking the time to go through > > the comparisons. > > > I was planning to build on the patch I posted before [1] to fix this > > problem once and for all (perhaps rather optimistically). > > > [1]http://sage.math.washington.edu/home/burcin/pynac/pynac_order.patch > > > Note that your suggestions fixes your bug (#9880), but doesn't effect > > #9046. > > > Cheers, > > Burcin > > -- To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
