That's a bit puzzling. In the Sage code, line 36 defines the manifold over
the real field. That is supposed to be inherited by the chart in line 39:

##
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M = Manifold(1*3,'R^3',field='real',start_index=1)
U = M.open_subset('U')
Rho.<r12,r13,r23> = U.chart("r12:(0,+oo) r13:(0,+oo) r23:(0,+oo)")
One therefore expects r12, etc. to be real.
- Richard
On Thursday, August 10, 2017 at 10:34:40 PM UTC-7, Robert Dodier wrote:
>
> On 2017-08-10, Richard_L <rich...@lozestech.com <javascript:>> wrote:
>
> > The following string sent to maxima causes a seg-fault and core dump:
>
> > '#$is
> >
> (equal(-(_SAGE_VAR_r13^2*_SAGE_VAR_r23-_SAGE_VAR_r23^3)/((-_SAGE_VAR_r23^4)+2*_SAGE_VAR_r13^2*_SAGE_VAR_r23^2-_SAGE_VAR_r13^4+_SAGE_VAR_r12^4),0))$'
>
>
>
> Looks like domain:complex and assume are both needed to trigger this
> error. declare(..., real) isn't needed to trigger it.
>
> ...
>
> A workaround might be to set domain:real instead of domain:complex.
>
> If someone can make a bug report and include these notes, that would be
> great. I didn't try to find a simpler example but maybe one exists.
>
> best,
>
> Robert Dodier
>
>
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