Hi, I'm trying you new integration code, and integrate(x^(1/3)/(3*x+1)^(1/3), x) >> Error detected within library code: impossible
what does this "impossible" mean? Is it a bug? BTW: Is sourceforge.net/p/fricas/bugs/ the proper place to report bug? Thanks. xyy 在 2014年11月27日星期四UTC+8下午7时35分21秒，Waldek Hebisch写道： > > I have now commited new extended integration code. The new code > is still quite incomplete and this is likely to lead to some > regressions. However, the old code was even more incomplete > so that on average we should see improvement. As one example > in fixed.input we have: > > integrate(((-x-1)*log((x^2+x))^2+2*log(x))/(x+1),x) > > That used to fail, but now produces correct result. Let > me add that old code on hitting incompltenss would silently > claim that function is not integrable. For elementary functions > new code will signal error for unimplemented parts. > > Let me add that unimplemented parts are about general algebraic > integrands (completely unhandled by old code), bounds in RDE > (old code makes assumption which may be invalid, new code > tries to solve parametric logarithmic derivative problem for > which no good complete algoritm is known) and RDE in general > algebraic case (again completely unhandled by old code). > > In several cases old code took a shortcut (usually via > substitutuin), which may lower execution time or handle > some cases that would be otherwise unhandled. Currently > new code takes almost no shortcuts. One reason is that > I tried to keep code simple (without extra cases). Also, > it is not clear how effective are the shotcuts (I suspect > that they help only a little). If there are performance > regressions I will add faster paths for important special > cases, but I prefer to do this only after having enough > evidence. > > -- > Waldek Hebisch > [email protected] <javascript:> > -- 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 post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/fricas-devel. For more options, visit https://groups.google.com/d/optout.
