oldk1331 wrote:
> On 7/14/19 9:26 PM, Waldek Hebisch wrote:
> > Real bug above is that we can not expand terms separately.
> > Concerning "pairsum": it should go away. I with attached
> > patch I get:
> >
> > (1) -> integrate(a^(1/4)/(x^8-1),x)
> >
> > (1)
> > 4+-+
> > --+ x\|a - 8 %E
> > > %E log(------------)
> > --+ 4+-+
> > 4 \|a
> > 4096 %E - a = 0
> > +
> > 4+-+
> > --+ x\|a - 8 %F
> > > %F log(------------)
> > --+ 4+-+
> > 4 \|a
> > 4096 %F + a = 0
> > Type:
> Union(Expression(Integer),...)
> >
> > Unfortunatly, this causes troubles for definite integrator.
> > Basically, we need to teach 'limit' how to handle 'rootSum'.
> >
>
> Shouldn't we try to simplify 'rootSum' with coefficients like
> "%E^4 +- a = 0"?
We should try to simplify when we can. My point is:
- 'rootSum' gives valid result when we can not simplify
- compared to 'rootSum' some transformations that we
currently do produce more complicated result, so
we should drop them
- once we have 'zeroOf' correct simplification is harder
than with 'rootSum'
- several simplifications depends on factorization. That
requires global point of view, that is we need to look
at all kernels.
Currently implementation does not look at interactions between
kernels and that is core of the problem.
--
Waldek Hebisch
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