[Debian-astro-maintainers] Bug#788699: stellarium: Hangs after moving to the past/future by several days

[Pawel T. Jochym]

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W dniu 15.06.2015 o 01:28, Tomasz Buchert pisze:
> On 15/06/15 00:46, Tomasz Buchert wrote:
>> [...]
>> Could it be a compiler bug that miscompiled the loop for
>> 0.13.3-2?
>
> I take it back, now I think it is not compiler issue (see below).  I
> extracted the parameters that make the loop infinite and made a
> minimal program that shows the problem (attached).
>
> As you can see, it converges quite rapidly, but finally |E-Ep| stays
> bigger than 1e-10 and E oscilates between 2 values. An engineer's way
> to solve it would be to let the loop run for, say, 100 iterations,
> and if it didn't converge, just show a warning.
>
> Cheers,
> Tomasz

Notice how close to parabolic this orbit is. Maybe we need a better
algorithm for this range of params. Also numerical conditioning may
be important in such a case.

P.

- -- 
Pawe? T. Jochym
Institute of Nuclear Physics, PAN
Cracow, Poland

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