Frenet formula
[ fre-ney ]
/ frɛˈneɪ /
noun Mathematics.
one of a set of formulas for finding the curvature and torsion of a plane or space curve in terms of vectors tangent or normal to the curve.
Origin of Frenet formula
named after their discoverer, Jean (or Frédéric)
Frenet (1816–1900), French mathematician