On Tue, 22 Aug 2000 17:06:35 -0500, Chris Huff wrote:
>One way to flip the inner function's sign would be to use an object 
>pattern, though I may add this capability to the pattern itself.
>And wouldn't this remove *all* the areas which are causing trouble with 
>the object pattern? 

Yes.  That is, it'd remove the surface of the object.

>And the axis of a cylinder/cone

Actually, not the axis.  For a cylinder, two cones at the ends, and the line 
segment connecting their apexes.  For a cone, a different cone at the base 
and the line segment connecting its apex with the containing cone.  
There are external places where it's undifferentiable as well.

>Isn't the maximum gradient used to help prevent missing 
>these intersections?

No.  It's used to help the solving algorithm know when there can't possibly
be a solution in the test interval.  I've been thinking about the problem,
though, and I think it might be okay after all if there are some isolated 
spots where it's not differentiable, so long as it's continuous.  After all,
min/max have the same problem.  This whole thread may be a false alarm.

-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.

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