Comment #6 on issue 636 by [email protected]: integrate(1/(x**2+1)) should return arctan(x) http://code.google.com/p/sympy/issues/detail?id=636
Converting complex exponentials to trigonometric functions is extremely difficult. (See another issue lurking on it.) The authors of "Algorithms for computer algebra" suggest: "A more practical approach generally adopted in computer algebra systems is to invoke initially a heuristic integration procedure which uses some standard transformations and table look-up (in the spirit of a classical first-year calculus student) to obtain the result in "familiar form" if possible. If the heuristic method fails then the problem is converted into the exp-log notation and the finite decision procedure is invoked. The result from the latter procedure will be either the integral expressed in the exp-log notation or an indication that there does not exist an elementary integral." I agree it would be good if we could reverse exp/log's into trig functions, however, until we find a good algorithm for it, it might be best if we just use a lookup table where possible (for the integrals). -- You received this message because you are listed in the owner or CC fields of this issue, or because you starred this issue. You may adjust your issue notification preferences at: http://code.google.com/hosting/settings --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sympy-issues" group. 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/sympy-issues?hl=en -~----------~----~----~----~------~----~------~--~---
