Mike Williams wrote:
> 
> [...]
> 
> The actual gradient of a polynomial function in the order of n*x^(n-1).
> So the sort of gradients that you'll encounter at the edges of your
> container change something like this:
> 
> n=4, container <-3,3>, gradient 4*3^3 = 36
> n=6, container <-3,3>, gradient 6*3^5 = 1458
> n=6, container <-2,2>, gradient 6*2^5 = 192
> 
> Because your max_gradient is set *way* too low, the solver simply
> evaluates the function at the edges of the container. It believes the
> value of max_gradient that you've given it and knows that the nearest
> surface point can't be closer than
>  (calculated_value - threshold) / max_gradient
> so there are "obviously" no surface points within the box.
> 

Ahhh!

Sometimes you don't see the obvious even if it's right in front of you...
(see also p.b.i.)

So it's important to say that the max_gradient value should be larger than
the gradient *everywhere* in the container, not only near the actual
surface.  

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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