#7334: Sage cannot simplify sums of logarithms
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Reporter: whuss | Owner: burcin
Type: defect | Status: needs_work
Priority: major | Milestone: sage-4.2.1
Component: calculus | Keywords: logarithm
Work_issues: | Author: whuss
Reviewer: | Merged:
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Changes (by kcrisman):
* status: needs_review => needs_work
Comment:
Here are a few comments, which you can incorporate if you agree with them.
Overall, though, a VERY well documented patch, which tells the user
exactly what they can and cannot do with it, options, etc. Good work!
1. typo of "gowerns" instead of "governs" in line 5268
2. Maybe the if coeff is not None: should be set off in a block? For
better readability and logical flow.
3. Perhaps
{{{
sage: (log(5)-log(2)).simplify_log()
-log(2) + log(5)
}}}
should be included as a doctest, with a comment that this is not
simplified (though it's not mathematically wrong, so I am okay with this
being as is). This will also encourage us to upgrade Maxima :)
4. There are some duplicated doctests. Is this intentional (i.e., to show
it won't simplify any more)? Since
{{{
sage: x,y,t=var('x y t')
sage: f = log(x)+2*log(y)+1/2*log(t)
sage: f.simplify_log()
log(x*y^2) + 1/2*log(t)
sage: f
1/2*log(t) + log(x) + 2*log(y)
}}}
it must have some other rationale. Anyway, that should be clarified, or
the duplicates should be removed, as this is confusing.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/7334#comment:9>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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