#17065: use Maxima's trigrat() in symbolic simplify
-------------------------------------+-------------------------------------
Reporter: rws | Owner:
Type: defect | Status: needs_work
Priority: major | Milestone: sage-6.4
Component: symbolics | Resolution:
Keywords: maxima, | Merged in:
simplification, trigonometric | Reviewers:
Authors: Ralf Stephan | Work issues:
Report Upstream: N/A | Commit:
Branch: | 3db6f899c380523dc6d6e940650eede5984a37fa
u/rws/use_maxima_s_trigrat___in_symbolic_simplify| Stopgaps:
Dependencies: |
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Comment (by rws):
Replying to [comment:5 kcrisman]:
> This can even lead to disaster, I think:
> {{{
> sage: F = (4*cos(9*pi/180)^2 - 3)*(4*cos(27*pi/180)^2 - 3)
> sage: F.maxima_methods().trigrat()
> sqrt(5) + 2*cos(7/10*pi) - 2*cos(1/10*pi) - 2*I*sin(3/5*pi) +
> 2*I*sin(2/5*pi) + 1
> }}}
> I really am not interested in seeing `I` turn up in such a
simplification, regardless of the "correct" answer.
While this one could be resolved by adding a `trigreduce` to the queue:
{{{
sage: F = (4*cos(9*pi/180)^2 - 3)*(4*cos(27*pi/180)^2 - 3)
sage: F.maxima_methods().trigrat()
sqrt(5) + 2*cos(7/10*pi) - 2*cos(1/10*pi) - 2*I*sin(3/5*pi) +
2*I*sin(2/5*pi) + 1
sage: _.maxima_methods().trigreduce()
sqrt(5) - 2*cos(3/10*pi) - 2*cos(1/10*pi) + 1
}}}
I cannot see how to fix the doctest failure:
{{{
File "src/doc/de/thematische_anleitungen/sage_gymnasium.rst", line 394, in
doc.de.thematische_anleitungen.sage_gymnasium
Failed example:
(sin(x + y)/(log(x) + log(y))).simplify_full()
Expected:
(cos(y)*sin(x) + cos(x)*sin(y))/log(x*y)
Got:
((-I*arctan2(0, x) - I*arctan2(0, y))*sin(x + y) +
log(abs(x)*abs(y))*sin(x + y))/(arctan2(0, x)^2 + 2*arctan2(0,
x)*arctan2(0, y) + arctan2(0, y)^2 + log(abs(x))^2 +
2*log(abs(x))*log(abs(y)) + log(abs(y))^2)
}}}
the minimal case being
{{{
sage: log(x).maxima_methods().trigrat()
I*arctan2(0, x) + log(abs(x))
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/17065#comment:8>
Sage <http://www.sagemath.org>
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