Nieminen Mika schrieb:
> Ralf Muschall <rmu### [at] t-onlinede> wrote:
> : Unfortunately, scaling and taking the derivative
> : (which is what creates the surface normal from the height)
> : are not exchangeable.

>   Are you sure?

> by definition:

>   d(a*f(x))/dx = a*d(f(x))/dx

This is not the problem, since it is not scaling (your a is
the parameter which is to be written after the keyword "bumps",
i.e. what the manual thinks it were the _height_ of the bumps).

Scaling affects the _argument_ of the function, and

(D g)(x) = b*(D f)(b*x)                 [1]

where
g(u):=f(b*u), and the operator D takes the derivative of
the function wrt. its argument.
[1] is essentially the chain rule, where the inner function
is the multiplication by a constant.

My b is the inverse of the parameter after the keyword
"scale". POV's (or my) problem is that the first "b*" on the
right hand side of equation [1] is missing (or left out
intentionally).

Ralf

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