Manifold-valueddatasetsarewidelyencounteredinmanycomputervisiontasks.Anon-linearanalogofthePCAalgorithm,calledthePrincipalGeodesicAnalysis(PGA)algorithmsuitedfordatalyingonRiemannianmanifoldswasreportedinliteratureadecadeago.SincetheobjectivefunctioninthePGAalgorithmishighlynon-linear