On Apr 11, 2011, at 4:12 PM, Alexey U. Gudchenko wrote: > 12.04.2011 01:56, Ronan Lamy пишет: >> Le lundi 11 avril 2011 à 15:42 -0600, Aaron S. Meurer a écrit : >>> On Apr 11, 2011, at 2:25 AM, smichr wrote: >>> >>>> Should `Integral(x, (x, 1, 2)) == Integral(y, (y, 1, 2))` be True? If >>>> so, smichr branch 2068b has a commit that makes this testing possible. >>>> >>> This is a good question. For one thing, == is not mathematical >>> equality but exact equality, so there is no reason why it should have >>> to be True. So my initial response is that no, it should not. >>> >> I think it should. x and y are bound symbols that have no meaning >> outside the integrals, so their identity should be completely >> irrelevant. In fact, they should probably be replaced with dummies upon >> instantiation of the Integral. >> >> > > Mathematically equal. (especially when assumptions for symbols are equal > too). > > Another question what means "==" in SymPy: mathematical > or not (pythonic?). > > Aaron, what do you mean by "exact equality"? > E.g Does the "Max(1, 2, x)" exact equal to the "Max(2, x)" or not? > > > -- > Alexey U.
"Exact" meaning it checks if the objects are equal. The usual example is that we have >>> (x + 1)**2 == x**2 + 2*x + 1 False I thought Max(1, 2, x) automatically reduced to Max(2, x). In that case, then, obviously they would be equal with ==. Also you would have Max(2, x) == Max(x, 2) because it internally uses a data structure that does not care about order (set or frozenset). Whenever you see == in SymPy, it is specifically assuming this exact/object equality. Another thing to consider is: In [190]: hash(Integral(x, (x, 0, 1))) Out[190]: -9173880960074697984 In [191]: hash(Integral(y, (y, 0, 1))) Out[191]: −299967655319032172 A == B should imply hash(A) == hash(B). Aaron Meurer -- You received this message because you are subscribed to the Google Groups "sympy" group. 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.
