https://5dok.org/document/y8gr07jw-howinterpolatingandsmoothingsplinescanbeapproachedusingthetheoryoflinearcontrolsystems-thisthesisincludesamathematcicalbackgroundthatissufficienttoreconstructseveraloftheirresults-includingsplinefunctionsonthecartesianplaneandontheunitsphere-egerstedtandmar.html