On Sunday, March 13, 2016 at 8:08:51 AM UTC-7, Eric Gourgoulhon wrote:
>
>
> Is this a known issue? Shall I open a ticket for it?
>
> I think it's known, but difficult to solve. Consider this:
sage: f1=function('f')
sage: f2=function('f')
sage: f3=function('f',latex_name='F')
sage: f1(x).operator() is f2(x).operator()
True
sage: f1(x).operator() is f3(x).operator()
False
sage: f2,f3
(f, f)
This illustrates what happens internally. As you can see, we end up with
two functions, with different latex_names (this should apply to other
attributes too), but they cannot be distinguished from their print names.
When they go through maxima, we cannot distinguish them anymore:
sage: [maxima_calculus(f) for f in [f1,f2,f3]]
[f, f, f]
For symbolics we have a similar problem but a different decision is made
(things are already squashed in the symbolic ring):
sage: a1=SR.symbol('a')
sage: a2=SR.symbol('a',latex_name='A')
sage: a1 is a2
True
sage: latex(a1) #note that a1 changed as a side-effect of defining a2
A
sage: [maxima_calculus(a) for a in [a1,a2]]
[_SAGE_VAR_a, _SAGE_VAR_a]
sage: [latex(SR(maxima_calculus(a))) for a in [a1,a2]]
[A, A]
As you can see, symbols already get translated to maxima with extra
information in their name: we prepend `_SAGE_VAR_`. We could extend that
further by adding other useful(?) information to the name, or store it in
properties on the symbol.
We could do the same thing with functions: we could translate their arity
(this is now lost, but isn't used anyway) into the symbol representing them
on the maxima side. In the process it might be nice to make the
representing sage objects a little more representative of the underlying
pynac objects too. Currently:
sage: function('f') is function('f')
False
sage: function('f')(x).operator() is function('f')(x).operator()
True
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