Re: problem with output of the program on different OS

On May 12, 10:44 pm, Ben Bacarisse <ben.use...@[EMAIL PROTECTED]
> wrote:
> pereges <Brol...@[EMAIL PROTECTED]
> writes:
> > 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=463
> >> (they are the same at ray_count=462).
>
> >> 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=462, 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).
>
> This is not a good way to debug a program.  Did you fix (or disprove)
> the apparent bug that I pointed out?  Using uninitialised data would
> explain all the variation in results.
>
> The probability of finding a compiler bug in language X is roughly
>
>  (epsilon + no. of years you've been programming in X)/N
>
> (for some small epsilon and large N) :-)


Yes, I fixed the bug that you had pointed out( uninitialized members
of E_incident and E_scattered) and other bugs that many people have
pointed out. Because of these changes, I'm now getting a different and
consistent result on most compilers. Other people are also getting the
same result as me now. Strangely, only pellesC is re****ting a
different result which is similar to the result I had before the bugs
were fixed. It doesn't seem to be affected by the changes.