#11888: Sage is missing the lambert_w function conversion from Maxima
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Reporter: benjaminfjones |
Owner: burcin
Type: defect |
Status: needs_work
Priority: minor |
Milestone: sage-5.0
Component: symbolics |
Keywords: lambert_w symbolics conversion maxima sd35.5
Work_issues: add second parameter, RDF/CDF stuff |
Upstream: N/A
Reviewer: Keshav Kini, Karl-Dieter Crisman, Fredrik Johansson |
Author: Benjamin Jones
Merged: |
Dependencies:
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Comment(by benjaminfjones):
After looking at this a bit more, it may be more involved than I initially
envisioned to implement arbitrary branches of the lambert_w function in
one symbolic function. Right now, the patch from SD 35.5 implements a
subclass of !`BuiltinFunction`. The underlying assumptions about
subclasses of !BuiltinFunction include: (from sage/symbolic/function.pyx)
{{{
We assume that each subclass of this class will define one symbolic
function.
}}}
One issue is that there isn't a way (as far as I can see) to pass a branch
parameter to !`BuiltinFunction`'s `_call_` method. (Perhaps burcin or
other authority on Sage symbolics can comment on this.)
Changing the evaluation numerical eval to use !SciPy would be an easy
change, that's for sure. I can do that quickly and upload a patch that
implements the principle branch only.
Another idea I just had was to do something like what we have for the
Bessel functions, in particular the !`Bessel` class in
sage/functions/special.py which is just a basic python class returning one
of the Bessel (I,J,Y) functions of a given order.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11888#comment:18>
Sage <http://www.sagemath.org>
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