Has there been any progress on integrals expressible in elliptic functions?
I need them now, and it seems that no open source integrators can compute things like integrate(sqrt(x*(x-1)*(x-2)),x=0..1) in terms of elliptic functions. Thanks Dima On Tuesday, October 23, 2018 at 8:01:25 PM UTC+1 Waldek Hebisch wrote: > I looked a bit at FriCAS failures in Rubi testsutite. More than > 8000 positions in testsutite contains elliptic integrals in > answer. FriCAS currently can not generate ellipic integrals > in answers, so unless the integral really is elementary > (it happens sometimes, but is quite rare) FriCAS can not > do it. This is more than 10% of the testsuite and single > biggest reason for failures. > > More about this: it seems that most elliptic cases is > very simple, easily reducing to defining formulas > by few substitutions. It seem relatively easy to add > ad-hoc handling for such cases. Main problem is that > we do not want to loose completeness for elementary cases, > so we can generate elliptics only after we decided that > integral is nonelementary. > > Probably next biggest problem is polylogaritms (of order 5000 > positions). We can handle one case, when argument of > polylogarithm is an exponential. But Rubi testsuite seem > to contain mostly different case. > > There are also integrals expressed in terms of hypergeometric > functions (few thousends). They are used to integrate > algebraic functions and some mixed cases involving > algebraics and exponentials. I need to look closer, > but at least some of them we should be able to handle > like existing code for incomplete gamma. > > Together the cases above seem to cover vast majority of > failures on Rubi testsuite. There are also failures > which current FriCAS methods in principle should handle, > but are not handled due to incomplete or buggy implementation. > > ATM better handling of the above is still in planning stage. > I have made nice theoretical progress, both for elliptic > functions and for polylogarithms. But in both cases > theory is still too weak to give complete algorithm. > So we probably should try adding ad-hoc extentions. > There is reasonable chance that such extentions will > be part of complete implementation in the future. > > -- > Waldek Hebisch > -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/fricas-devel/24a7f415-bec6-49ec-b98f-94eb188a88ecn%40googlegroups.com.
