代码：
C0 = 0; B1 = [2 4; 3 1]; A1 = [1 1 0.9; 1 0.4 -0.4]; B2 = [0.5 0.7; 1.5 2.5; 0.8 1]; A2 = [1 -1 0.8; 1 0.5 0.5; 1 0 -0.5]; [b1, a1] = par2dir(C0, B1, A1) [b2, a2] = par2dir(C0, B2, A2) b = conv(b1, b2) % Overall direct form numerator a = conv(a1, a2) % Overall direct form denominator [b0, Bc, Ac] = dir2cas(b, a) % Overall cascade form [C0, Bp, Ap] = dir2par(b, a) % Overall parallel form
运行结果：
根据系数写出相应的公式：
《DSP using MATLAB 》示例Example6.3
原文：http://www.cnblogs.com/ky027wh-sx/p/6274812.html