On 27/03/2026 00:13, Bald Eagle wrote:
> I've been working on making my vector arity macro robust, and I came across this
> surprising fact while stress testing.
> 
> NAN is treated differently in the parser than in the function VM.
> 
> NAN equals - EVERYTHING in the parser.
> 
> NAN equals nothing, not even itself in the function VM.
> 
> So my IfNan () macro fails, but my IfNan () function works as expected.
> 
> I'll need to dig into this and see where in the source it goes wrong.
> 
> I also recall seeing a thread where people were playing with N/0, and I think
> the parser biases that - probably because it allows certain code to keep going.
> 
> https://news.povray.org/44294a5a%241%40news.povray.org
> 
> - BE
> 




Tim Nikias's message does not specify a POV version.
But, mathematically speaking, it makes sense :

lim      1/x = +∞ and    lim      1/x = -∞
x -> 0+                  x -> 0-

but no NAN.



In version 3.8 this code
	#declare a = 1/0;
	#debug concat("a = ",str(a,0,-1),"\n")

Give :
	Parse Warning: Divide by zero.
	a = inf

Only parse warning. No stop error in parser.


It is reasonable to assume that 1e+017 is equivalent to ∞




-- 
kurtz le pirate
compagnie de la banquise

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