For the purpose of the Frenet sweep only, you may use:
It eliminates collinearities but its output will not be appropriate to BzEnergy() digestion. 2017-12-27 14:23 GMT-02:00 Ronaldo Persiano <[hidden email]>:
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In reply to this post by nophead
As I have supposed the instability was produced by BestBz(). I had to tighten the stopping clause in _bestS to get a better stability. I can't assure this method is foolproof; it may go wild when the tangent directions and endpoints induce a loop or inflexions to the arc. Besides, to avoid stack overflow I limited arbitrarily the maximum number of recursions calls.
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That is really true. I found a case where the energy curve as a function of the balance s has 3 local minima. bzcp=[[0, 0, 0], [0, 0, -125.85], [0, 9.721, 32,14], [0, 79.721, 32,14]]; length=180; For each minimum there is a stable cubic solution as shown bellow. The blue curve has the smallest energy for a balance s=0.78. The yellow one has the greatest energy for a balance s=0.04. The green curve was the one found by my code with a balance s=0.39 and a total energy 10 times of the blue curve and 74% of the yellow one. All three curves are local minima of the energy function and I doubt that any of them is a good approximation of an elastica. _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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