On Sat, Dec 1, 2012 at 9:32 AM, Aaron Meurer <asmeu...@gmail.com> wrote: > I guess it's not necessarily a good idea to auto-expand things like > binomial(n, 5). Go ahead and open another issue for that if you want. > Probably it should be changed to remain unevaluated, and to expand > with expand(func=True).
Hi Aaron, before I report that, does the doit() automatically call an expand()? Ideally what we expect is I should get: t*Sum(n*(-1)**(1 + j)*binomial(1, j)*ival(j), (j, 0, 1)) + Sum((-1)**j*binomial(0, j)*ival(j), (j, 0, 0)) + t**3*Sum(n*(-1)**(3 + j)*(-1 + n)*(-2 + n)*binomial(3, j)*ival(j)/6, (j, 0, 3)) + t**4*Sum(n*(-1)**(4 + j)*(-1 + n)*(-3 + n)*(-2 + n)*binomial(4, j)*ival(j)/24, (j, 0, 4)) + t**2*Sum(n*(-1)**(2 + j)*(-1 + n)*binomial(2, j)*ival(j)/2, (j, 0, 2)) + t**5*Sum(n*(-1)**(5 + j)*(-1 + n)*(-4 + n)*(-3 + n)*(-2 + n)*binomial(5, j)*ival(j)/120, (j, 0, 5)) but with the Sums actually evaluated. BTW try copy-pasting the above (which is nothing but the output of sstr as you had suggested) into IPython and hitting enter, and again there is an infinite loop. If I replace the Sum by summation then I get: t**5*(-n*(n - 4)*(n - 3)*(n - 2)*(n - 1)*ival(0)/120 + n*(n - 4)*(n - 3)*(n - 2)*(n - 1)*ival(1)/24 - n*(n - 4)*(n - 3)*(n - 2)*(n - 1)*ival(2)/12 + n*(n - 4)*(n - 3)*(n - 2)*(n - 1)*ival(3)/12 - n*(n - 4)*(n - 3)*(n - 2)*(n - 1)*ival(4)/24 + n*(n - 4)*(n - 3)*(n - 2)*(n - 1)*ival(5)/120) + t**4*(n*(n - 3)*(n - 2)*(n - 1)*ival(0)/24 - n*(n - 3)*(n - 2)*(n - 1)*ival(1)/6 + n*(n - 3)*(n - 2)*(n - 1)*ival(2)/4 - n*(n - 3)*(n - 2)*(n - 1)*ival(3)/6 + n*(n - 3)*(n - 2)*(n - 1)*ival(4)/24) + t**3*(-n*(n - 2)*(n - 1)*ival(0)/6 + n*(n - 2)*(n - 1)*ival(1)/2 - n*(n - 2)*(n - 1)*ival(2)/2 + n*(n - 2)*(n - 1)*ival(3)/6) + t**2*(n*(n - 1)*ival(0)/2 - n*(n - 1)*ival(1) + n*(n - 1)*ival(2)/2) + t*(-n*ival(0) + n*ival(1)) + ival(0) which is the same doit() output I guess. What we would expect as an "ideal" output would be: t**5*binomial(n,5)*(-ival(5) + binomial... something like that. So if you could advise me on how exactly to word the subject of the bug I can report it. -- Shriramana Sharma -- 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.
