摘要
Denote the nth, mth-order polynomial sets(n】m) with real coefficients as F={f(z)|f(z)=a<sub>0</sub>z<sup>n</sup>+a<sub>1</sub>z<sup>n-1</sup>+…+a<sub>n-1</sub>z+a<sub>n</sub>,a<sub>0</sub>≠0}, G={g(z)|g(z)=b<sub>0</sub>z<sup>m</sup>+b<sub>1</sub>z<sup>m-1</sup>+…+b<sub>m-1</sub>z+b<sub>m</sub>, b<sub>0</sub>≠0}.For any f(z), if all its roots lie within the unit circle, then f(z) is said to be astable polynomial in the discrete time sense, and denoted as f(z)∈S. For any g(z)∈G, f(z)∈F∩S,