WeestablishtheconstructiontheoryoffunctionbaseduponalocalfieldKpasunderlyingspace.Byvirtureoftheconceptofpseudo-differentialoperator,weintroduce"fractalcalculus"(or,p-typecalculus,or,Gibbs-Butzercalculus).Then,showtheJacksondirectapproximationtheorems,BermsteininverseapproximationtheoremsandtheequivalentapproximationtheoremsforcompactgroupD(Kp)andlocallycompactgroupK+p(=Kp),sothatthefoundationofconstructiontheoryoffunctiononlocalfieldsisestablished.Moreover,theJacksontype,Bernsteintype,andequivalentapproximationtheoremsontheH?lder-typespaceCσ(Kp),σ>0,areproved;thentheequivalentapproximationtheoremonSobolev-typespaceWrσ(Kp),σ≥0,1≤r<+∞,isshown.
