Hi There,
Follow up from thread "indexed symbolic variables".
> > > Do we have to call Maxima to compute the numerator of a rational
> > > fraction ? Is seems to me that Pynac/Ginac should be able to do it by
> > > themselves.
> > >
> > Unfortunately, we still call maxima for a lot of trivial operations.
>
> This is now #12068
To speedup some computation I'm trying to wrap Ginac numer and denom method.
Thanks to Cython, this is very easy. However, Maxima and Ginac have a
different semantic for those two functions:
- Maxima: Does not change the expression; if the expression is not a
quotient, then this will return the expression itself.
- Ginac: try to normalize the expression to put it in the form N/D and then
return N;
For example, with an expression such as "x + y/(x + 2)",
- Maxima: numer = x + y/(x + 2), denom = 1
- Ginac: numer = (x^2 + 2x + y), denom = x + 2
I can more or less emulate Maxima's behavior with Ginac, but I'm not sure
what's best to do. I see several options:
1 - Forget about Maxima and follows Ginac semantic;
2 - Follows Maxima semantic as close as possible using Ginac;
3 - Have a parameter 'algorithm' to select the needed one. Depending one the
algorithm the semantic differ;
4 - Have a parameter 'normal' to select if we normalize or nor the result
before computing the numerator, always use Ginac however.
5 - 3 and 4, have two parameters, one for selecting Maxima or Ginac, one for
performing a normalization before.
6 - other options ???
In case 3, 4, 5, we also should decide what is the default.
What do you think ?
Cheers,
Florent
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