GM(1,1)isgenerallyusedinGreySystemTheorywhichconstructsanOrdinaryDifferentialEquationforgivense-ries.Itiseffectiveformonotoneseries,anditssimulatingeffectisgoodanderrorissmall.However,Iftheseriesdosen’thaveapropertyofmonotone,thesimulatingeffectofGM(1,1)isnotfine,anditserrorgetsbigger.Inthispaper,weuseGM(2,1)tohandletheoxcillationseries,whichusestheMethodofMinimumSquaresindeterminingtheuncertainparameters.The
