23 lines
682 B
Matlab
23 lines
682 B
Matlab
function H=iir_pade(r,a,n,T)
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% iir_pade - design IIR filter with Pade approximants
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%
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% H=iir_pade(r,a,n,T)
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%
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% r - the fractional order
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% a - weighting factor
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% n - the filter order
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% T - sample time
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% Copyright (c) Dingyu Xue, Northeastern University, China
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% Last modified 18 May, 2022
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arguments, r(1,1) double, a(1,1){mustBeInRange(a,0,1)}=0
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n(1,1){mustBePositiveInteger}=3
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T(1,1){mustBePositive}=0.01
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end
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syms x, b=(3+a-2*sqrt(3*a))/(3-a);
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k0=6*b/T/(3-a); f=((1-x^2)/(1+b*x)^2)^r;
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c=taylor(f,x,'Order',2*n); c=sym2poly(c);
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c=c(end:-1:1); [N,D]=padefcn(c,n-1,n);
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H=k0^r*tf(N(end:-1:1),D(end:-1:1),'Variable','z^-1','Ts',T);
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end
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