On Tue, Aug 08, 2023 at 04:06:20PM -0700, 'Nasser M. Abbasi' via FriCAS -
computer algebra system wrote:
> I can't understand this behavior of 1.3.9. Starting with fresh session, it
> seems the result one time works, and another time fails, using same exact
> command. Sometimes trying twice it works.
>
> >fricas --version
> FriCAS 1.3.9
> based on sbcl 2.3.0
>
> --------------------------------------------------------
> 1) -> unparse(integrate((2+3*x)/(2^(2/3)-x)/(x^3-1)^(1/2),x)::InputForm)
>
> >> Error detected within library code:
> catdef: division by zero
<snip>
>
> So you see, it seems Fricas does not always generate same result. It seems
> random to me. There many such integrals that generate division by zero, but
> it seems if one tries again it can work.
This is an old problem. FriCAS uses (pseudo)random numbers. In case
above FriCAS evaluates several rational functions at a random point.
If any of denominators evaluates to 0, then we get error as above.
This part probably should be rewritten, but correct code is going
to be much more complicated than current code.
--
Waldek Hebisch
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