On Wed, Mar 28, 2012 at 6:12 AM, Tom Bachmann <e_mc...@web.de> wrote: > Note also that, for computing with residues, you don't need a precise list > of the poles, just a *superset*.
This reminds me of another point. Aside from symbolic parameters changing the contour needed for convergence, it can also change where the poles are. For example, if you end up with a contour around the unit circle, and one of your poles is a*I, then answer will depend on |a| (whether it is < or > than 1). You need to consider how to express this for multiple parameters, and for potentially more complicated contours. Aaron Meurer > Just as you don't need precise knowledge of > the growth of the function, just an upper bound (although here you probably > want to be tighter). So it might be best to look at all parts of an > expression in turn to determine the poles (i.e. recursively apply poles(f+g) > = poles(f) union poles(g), same for multiplication etc.) I think if you use solve(1/expr) to find the poles, then solve will do this for you (addition and multiplication will both become multiplication in that case, and solve already splits apart expressions into multiplicative factors). Chris can correct me if I'm wrong. Of course, if you're trying to be rigorous and only allow specific forms that you know you can find all the roots for, you will have to be more careful. It will probably be best to implement that in solve, though. Aaron Meurer > > > On 28.03.2012 12:05, Chris Smith wrote: >> >> >> >> On Wed, Mar 28, 2012 at 4:42 PM, arpit goyal <agmp...@gmail.com >> <mailto:agmp...@gmail.com>> wrote: >> >> Aaron , >> I looked the code ,and then then tested the working >> solve(x*cos(x),x) the answer was very accuraely given (not all x for >> cos(x) was shown or general solutions was not shown ) but >> solve(x**2*cos(x),x) , NotImplementedError: Unable to solve the >> equation. >> >> >> Be sure to get the current master since there, >> >> >>> solve(x**2*cos(x),x) >> [0, pi/2] >> >> -- >> 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. > > > -- > 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. > -- 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.
