Ux =y 11x1+12x2+…+41,m-2Xn-2+41,m-1xn-1+ uinXn y1, u22X2+…+l2,n-2Xm-2+l2,n-1Xn-1+l2mXn=y2, un-2,n-2Xm-2+ln-2,n-1Xn-1+4n-2,nXn=yn-2, Un-1,n-1Xn-1 Un-1nXn yn-1: ln,nxn=yn· -(-左小