Le_Forgeron <jgr### [at] freefr> wrote:

>
> Caveat: 3D vectors are using floating point arithmetic, strict equality
> is unlikely to occurs due to noise on floating point operations. (e.g. :
> A=<2,4,5>/10; B=<2,4,5>/20; C=B+B+B; D=A+B; ... does D == C ? not sure!)
>

That's something fundamental that I didn't know. But I just always assumed that
POV-Ray took care of the floating-point discrepancy internally (as Warp
indicates), i.e. safely truncating the errors in some way. Put a different way:
I haven't *noticed* any oddities in my scenes.

Using an even simpler case:  something like #if(1/1 = 1) would cause havoc if it
was only 'statistically' TRUE due to floating-point errors. *Hopefully* that's
not the situation! :-O

It raises a question in my mind, though: Given a particular math equation on an
unchanging set of values, are the floating point errors always the same? As in,
frame-by-frame animation?

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