On Sat, 18 Jul 2009 09:49:19 -0300
Golam Mortuza Hossain <gmhoss...@gmail.com> wrote:
>
> Hi,
>
> In new symbolics, the default symbolic variables are complex.
> However, sometime it is useful/desirable to make the domain of
> variables to be real.
>
> Currently, there are no way to specify the domain of variables
> in Sage although underlying Ginac allows it. For example: following
> would to be good to have.
> ------
> sage: var('x,y,z', domain='real')
> ------
>
> Also, "assume" should be fixed so that it updates the domain.
> Currently it doesn't do so.
> --------
> sage: conjugate(x)
> conjugate(x)
>
> sage: assume(x, 'real')
> sage: assumptions()
> [x is real]
>
> sage: conjugate(x)
> conjugate(x)
> --------
>
> I could implement above rather easily by exposing underlying Ginac
> feature. However, I am not sure how to submit patches for pynac/ginac
> as its not under "devel/sage".
I don't think you need to make changes in pynac to make this happen.
You should be able to get away with adding a few definitions in
sage/libs/ginac/decl.pxi, and changing the var() function to allow
domain arguments.
This page contains some instructions to start developing pynac:
http://wiki.sagemath.org/symbolics/pynac_todo/push#LatestPynacspkg
I should probably move that to the pynac web site.
Cheers,
Burcin
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