MultigridSolverforscalarellipticlinearPDEsThePDEspecificationsneedtohavetheformatusedbythePDEtoolbox.Thegeometrydescription'g'andtheboundaryconditiondescription'b'caneitherbethenameofafunctionfile(seetheMatlabhelptopdegeomandpdeboundforgandb,respectively)or