Does anyone know of a grass hopper solution or a rhino solution to select points fo zero curvature along a a curve? These points would represent the peaks and troughs along a curve.
I read your post again:
1. the points of zero curvature aren't the same as peaks and throughs.
2. to find those you'll need to define a coordinate system (xy) first, then look for points, at which the curve's tangent vector is parallel to x.