Actually, I think that this is what povray does:

if I say,               noise3d (x^a                            ,  y,z)
it processes        noise3d (sign(x)*pow(abs(x),a),  y,z)

I will try to prove this tonight.
[I thought someone had asked what SHOULD it do--was that note deleted?]  If
povray processes the formula above as I described, there's no problem--it was
just a mystery to be solved . . .


david sharp wrote:

> > function {noise3d(x^3.0, y, z)}, I will bet, behaves correctly, and has
> > a kind of symmetry like the curve y=x^3.
>
> Because x^3.0 actually does x*x*x
>
> > There is something "more wrong" here.  If Ron were correct, then x^3
> > would also be symmetric about x=0.
>
> Ron didn't claim x^3 was (abs(x))^3. I  prematurely did claim that, and
> I was horribly, sorrowfully, and disgustingly mistaken.
>

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