[PyX-devel] Curves with infinite curvature

[Michael S. <m-s...@us...>]

Hello,

I have hit a problem concerning the geometry things of the normpaths.
Consider a Bezier curve that contains a point with infinite curvature.
This is very easy to produce by setting e.g. the last two points to
the same coordinates

  n = normcurve_pt(0,0, 1,1, 1,0, 1,0)

The curveradius_pt returns "None" for parameter value 1. But the
trafo/rotation does something quite unexpected. The tangent vector

  n.rotation([0.999999])[0].apply_pt(1, 0)

seems to converge against (-1, 0) while adding more "9"s to the
parameter. However, the tangent at the parameter value 1 is (1, 0).

My question now is, how well do we want to really reproduce the true
underlying geometry? We should return "None" for the rotation at such
points also.

Michael.

-- 
"A mathematician is a device for turning coffee into theorems"
  Paul Erdös.