194 CHAPTER 9.SISO DESIGN FOR UNSTABLE SAMPLED-DATA SYSTEMS underdetermined and B,...,3can be obtained as the minimum norm solution. Note that for M=2 one should select w >2 in order to avoid the trivial solution f（）=1. The case 6=1,1 was examined in detail in Sec.8.2.Let us now examine the common case where $1,but mi=1 for i=2,...,6.Then (9.3-1) is equivalent to: dk 1-je川=0，k=0,m1-1 (9.3-5a) f元：=1，i=2,,ξ (9.3-5b) The following theorem hoids: Theorem9.3-1.For:=1.S≥2，m:=1fori=2.,ξ，the coefficients 80.....3w must satisfy 9=-8-..-3w 9.3-6) )-1 ξ-1 {2)-1 八 -Q/(1-a) ≥Y 9.3-7) 0 n:-1 0 where 。。 = 9.3-8 and the elements vij of the m.-x w matriz Nw are defined by (8.2-6) 0 for i>j fori≤j (8.2-6) Proof.Follows directlyfrom T5.2-1,(9.3-5)and the fact that f(1)=1. Forξ=1，Thm.9.3-1 reduces :o Thm.8.2-1.Form:=1.the choice w=ξ-l. reduces (9.3-7)to the Vandende form (5.3-4).In general one should select w1=+m-2 and obian 3:.....as the minimum norm solution to (9.3-7小