Re: problem with output of the program on different OS

On May 12, 2:29=A0pm, pereges <Brol...@[EMAIL PROTECTED]
> wrote:
> Bart wrote:
> > Been trying to investigate further, but's it's getting more complex
> > and Pelles' IDE is a right pain to use.
>
> > The figures for radar->E_scattered start to divulge at ray_count=3D463
> > (they are the same at ray_count=3D462).
>
> > The immediate culprit is r.pathlength, but this is traced to
> > intersect_triangle(). I stored the last det value calculated in
> > intersect_triangle, and the results were for ray_count=3D462, 463,
464:
>
> > 0.550692 0.550692 0.329331 on main compilers
> > 0.550692 0.329331 0.329331 on Pelles C
>
> > Why is the middle one different? Might be a different pattern of
> > calling intersect_triangle(), which is where it starts to get
> > complicated.
>
> > Perhaps you should forget Pelles C. You might do a lot of work just to
> > discover some obscure bug in the compiler (on the other hand, you
> > might well find some undefined behaviour in your program and maybe all
> > the results were wrong).
>
> I really don't know and now its not even the question of incorrect
> output on different operating systems. Now, when I run the code on
> linux, I get the same output everytime for the same set of input(this
> was a problem previously).- Hide quoted text -

I had a further look at Pelles C version (now that I can run it from
the command line, I can make progress..)

With 3 compilers, ray 463 hits only triangle 654 of the 1200
triangles.

With Pelles C, ray 463 hits triangles 654 and 745, at equal distances.

Varying your EPSILON made no difference.

So it starts to look more like some strange numeric problem; perhaps
Pelles C does some calculations a little differently, or perhaps
something more serious; this requires more investigation by someone
with a lot more time!

It could still be a bug in /your/ calculations which may depend too
heavily on some very small value which is treated differently between
different C systems.

BTW this is a hell of a complicated program; I wouldn't have used C
for this. Not until it was 100% working with some reference results
anyway. (I(/we?) still don't know what the right output is supposed to
be. Makes testing a little difficult!)

--
Bartc