#17468: Strange integration error/hang with log(abs(sin(x)))
-----------------------------+----------------------------
Reporter: kcrisman | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.5
Component: PLEASE CHANGE | Keywords:
Merged in: | Authors:
Reviewers: | Report Upstream: N/A
Work issues: | Branch:
Commit: | Dependencies:
Stopgaps: |
-----------------------------+----------------------------
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!
--
Ticket URL: <http://trac.sagemath.org/ticket/17468>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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