The Maxima team has opened two bug reports about this issue: incorrect dilogarithm limit in definite integral & incorrect trig substitution:
https://sourceforge.net/p/maxima/bugs/4368/ and https://sourceforge.net/p/maxima/bugs/4369 OHappyDay schrieb am Samstag, 7. September 2024 um 17:20:08 UTC+2: > I have reported this to the Maxima team. > > wdjo...@gmail.com schrieb am Donnerstag, 5. September 2024 um 15:19:02 > UTC+2: > >> On Thu, Sep 5, 2024 at 9:16 AM 'OHappyDay' via sage-support < >> sage-s...@googlegroups.com> wrote: >> >>> I recently stumbled upon something that looks like a bug: >>> >>> Try to integrate the following function: >>> >>> f(x)=log(1-4*cos(x)+4) >>> integrate(f,x,0,pi) >>> >>> According to the following video ( >>> https://www.youtube.com/watch?v=nscSDYApAjM) the result should be >>> >>> 2*pi*log(2) >>> >>> But my local Sage as well as online I get this result: >>> >>> 1/12*I*pi^2 + pi*log(3) - 1/2*pi*log(9/4) + 1/2*I*log(2)^2 - I*dilog(2) >>> + I*dilog(-1/2) + I*dilog(-2) >>> >>> which is a complex number instead. >>> >> >> This could be a bug in Maxima: >> >> sage: CC(integrate(f,x,0,pi, algorithm='sympy')) >> >> 4.35517218060720 >> >> sage: CC(integrate(f,x,0,pi, algorithm='maxima')) >> >> 4.44089209850063e-16 - 3.28986813369645*I >> >> sage: CC(2*pi*log(2)) >> 4.35517218060720 >> >> >>> >>> Similarly this function >>> >>> g(x)=log(1-cos(x)+1/4) >>> integrate(g,x,0,pi) >>> >>> results in >>> >>> 1/12*I*pi^2 - pi*log(3) + 1/2*pi*log(9/4) + 1/2*I*log(2)^2 - I*dilog(2) >>> + I*dilog(-1/2) + I*dilog(-2) >>> >>> although it should be ZERO. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "sage-support" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to sage-support...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/sage-support/d3714f3c-b193-4d32-9d44-8a5a6d8ec5f1n%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/sage-support/d3714f3c-b193-4d32-9d44-8a5a6d8ec5f1n%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/a1ecb9f5-197b-4f0d-8f99-7bb7bc41c597n%40googlegroups.com.