#16439: Allow inverse trig functions to all take complex input
-------------------------------------+-------------------------------------
Reporter: kcrisman | Owner:
Type: defect | Status: needs_review
Priority: minor | Milestone: sage-6.3
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/ppurka/allow_inverse_trig_functions_to_all_take_complex_input|
c4ba30d802f932b29205ec3f49f3eeeeb0942e76
Dependencies: | Stopgaps:
-------------------------------------+-------------------------------------
Comment (by ppurka):
Replying to [comment:9 kcrisman]:
> Anyway, then it goes to the `arcsin()` ''method'' in
sage.symbolic.expression.Expression (!) because now we have a symbolic
expression for the previously `complex` input. And I'm pretty sure that
this is where things go wrong, because
[http://git.sagemath.org/sage.git/tree/src/sage/symbolic/pynac.pyx#n1596
here] it looks like it tries to coerce our now-symbolic thing to `RR`,
which of course we can't do.
Ah. I didn't figure out this step. I understood that it goes into
`Function`, but lost track from there.
> The reason your fix for the other arc trig functions works is because
they are not defined in Ginac/Pynac. But these functions don't work with
complex input, presumably because
[http://www.ginac.de/reference/inifcns__trans_8cpp_source.html#l00642
here] it doesn't handle complex stuff, or maybe because when we replaced
Ginac's internal numbers with Sage ones something happened.
Yes. I know. These functions have their own `_evalf_` method which gets
executed finally. What is weird is that there are some other functions
like `sec`, `csc`, etc, which also have an `_evalf_` method, but that
method probably never gets called! Instead the `_eval_` method gets
called. And, somehow that `_eval_` method takes care of `complex` type
input.
> Though as you say if we can't get it done quickly enough here, we can do
this stuff and open a new ticket for it. But I really don't like that
coercion to SR of complexes.
Yes, all this multiple coercion is unclear to me also. `SR` is slow; and
we should avoid doing those kinds of coercion. The only time when that
should be done is when `hold=True` is passed as a parameter.
--
Ticket URL: <http://trac.sagemath.org/ticket/16439#comment:11>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sage-trac.
For more options, visit https://groups.google.com/d/optout.
