iir_frac.m

高等引用数学的matlab求解的配套程序

function H=iir_frac(r0,a,n,T)
syms x r b; aas=((1-x^2)/(1+b*x)^2)^r; n2=2*n; b0=(3+a-2*sqrt(3*a))/(3-a);
aas=char(subs(aas,{r,b},{r0,b0}));
maple('with(numtheory)');  maple(['cfe:=cfrac(' aas ',x,n2)']);
p=collect(maple('nthnumer','cfe',n2),x); n=sym2poly(p);  
q=collect(maple('nthdenom','cfe',n2),x); d=sym2poly(q); 
H=tf(n(end:-1:1)*(6*b0/T/(3-a))^r0,d(end:-1:1),'Variable','z^-1','Ts',T);