> What if either argument is something like x - y or y - x? Would those both be canonicalized to the same thing (with either choice)?
No. a) We pull out some factors and get legendre objects of same argument: In [6]: legendre(n, y-x) Out[6]: (-1)**n*legendre(n, x - y) In [7]: legendre(n, x-y) Out[7]: legendre(n, x - y) b) Nothing happens beside what sympy does with the "Add" In [6]: legendre(n, x-y) Out[6]: legendre(n, x - y) In [7]: legendre(n, y-x) Out[7]: legendre(n, -x + y) - If there ever could be a case where someone would not want it changed, go > with option b, because, as with all automatic simplifications, option a > makes it impossible to not have it applied. > At the moment I see no reason to do so. But this does absolutely not mean that there never will be a reason. > I personally would vote for option a as it would be consistent with functions like sin and cos. Me too. Most objects do some simpler transformation at this point. Option b) is probably an overkill in turning off automatic simplification features, compared to the rest of sympy. -- You received this message because you are subscribed to the Google Groups "sympy" group. To view this discussion on the web visit https://groups.google.com/d/msg/sympy/-/jUEDJo-rQpAJ. To post to this group, send email to sympy@googlegroups.com. To unsubscribe from this group, send email to sympy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
