pub fn intrinsic_chord_bound3(curve: &Intrinsic3, a: f64, b: f64) -> Option<f64>Expand description
Certified chord bound of a 3D intrinsic curve over [a, b]: h^2 / 8 sigma sup |k|, whatever its torsion (|c''| = |k|). None outside
[0, length] or for a curvature law with no closed-form bound.