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Trac #17468: Strange integration error/hang with log(abs(sin(x)))
Here is something that hangs. {{{ sage: var('u') u sage: integral(log(abs(2*sin(u))), u, 0, pi/3) }}} Interestingly, we get {{{ sage: maxima_calculus('integrate(log(abs(2*sin(u))), u, 0, %pi/3)') #0: extra_integrate(q=(g93030^2+1)*(4*g93030/((g93030^2+1)*abs(g93030))- 8*g93030*abs(g93030)/(g93030^2+1)^2)/abs(g93030),x=g93030) ------------------------------------------------------------------------ --- TypeError }}} but in the shell, we get {{{ (%i1) integrate(log(abs(2*sin(u))),u,0,%pi/3); sqrt(3) %i + 1 sqrt(3) %i + 1 (%o1) (18 %i li (--------------) + 18 %i li (- --------------) - 3 %pi log(3) 2 2 2 2 2 2 %pi log(3) %i %pi + 2 %i %pi )/18 + ---------- - ------- 6 12 }}} The problem in Sage directly is {{{ (%i1) load(abs_integrate); (%o1) /Users/karl.crisman/Downloads/sage/local/share/maxima/5.34.1/share /contr\ ib/integration/abs_integrate.mac (%i2) integrate(log(abs(2*sin(u))),u,0,%pi/3); log: encountered log(0). }}} after which it hangs, and I'll report that upstream. But I don't know what the error in `maxima_calculus` is! URL: https://trac.sagemath.org/17468 Reported by: kcrisman Ticket author(s): Frédéric Chapoton Reviewer(s): Peter Bruin
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