#12780: Be more careful about setting the Maxima 'domain'
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Reporter: mjo | Owner: burcin
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.1
Component: symbolics | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: #12845 | Stopgaps:
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Comment (by mjo):
Replying to [comment:4 kcrisman]:
> I like the concept of allowing the switch. So you're sure that
`domain` is ignored for `radcan` and for whatever is going on with the log
simplify? Just asking.
Dr. Fateman recently (March 14) mentioned on the Maxima list that `radcan`
was written before Maxima's assumptions framework, and that all
simplification takes place outside of `radcan`.
I think we can allow the switch where it makes sense. I left the `domain:
real;` call in `expand_log()` alone because it only makes sense to call
`expand_log()` on a real argument.
With `simplify_log()`, it's less clear. Right now, if I do,
{{{
sage: f = sqrt(x**2)
sage: f
sqrt(x^2)
sage: f.simplify_log()
abs(x)
}}}
we silently convert the expression to the reals. This isn't a result of
the log simplification algorithm; it's a side effect of setting the domain
to real (which provides no other ''tested'' benefits).
Obviously assuming that you're working over the reals can allow some
simplifications, but we should just make that available to the user rather
than doing it arbitrarily in some simplification functions but not others.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12780#comment:5>
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