"Tim Nikias" <JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote in 
message news:4427d830$1@news.povray.org...
>> i don't know. povray'programmers team should provide you more about
>> that
>
> Well, then let this post be my cry for help to the programmers! :-)
>
> I'm not sure, I've tried simply successively dividing by 2 or 10 to get
> smaller and smaller numbers. Interesting enough is that when you divide 1 
> by
> 10 and use str(Value,1,50) you find another fraction somewhere (but this 
> is
> of course floating point arithmetic and the troubles associated with it,
> just interesting to see it in person). Neither of the two methods get me a
> QNAN though, the only thing I ended up with when building a number by hand
> (using a while-loop to add "0"s behind the comma and a "1" at the end) was 
> a
> string too long error.
>
> Another interesting thing to note is that I'm starting to think that this
> QNAN is more a problem with vectors than with single floating point 
> values.
> Cause everytime I get the QNAN in my matrix-output (which I simply output 
> as
> 3 vectors for the three axis') I get the QNAN in x, y and z, not just a
> single spot of the vector. OTOH, the vector-arithmetic might end up with 
> an
> invalid vector (using vcross a few times to build a matrix out of a few
> vectors) and thus get me the QNAN in every dimension... Well well, gotta 
> go
> look further until some POV-Ray-programming-wiz stumbles upon this post 
> and
> knows where to look. :-)
>
> Regards,
> Tim
>

Hi TIm,
I tried to write out a few different things that I thought might be invalid, 
but I didn't manage to generate any QNANs.
I would suggest doing a tool that will let you do a multi-file search on 
'QNAN' against the POV-Ray source to give you some idea about the type of 
circumstances in POV-Ray that can lead to a QNAN. I can't imagine there'll 
be that many.

Regards,
Chris B.

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