stepresp.m

这是一个优化IIR滤波器的源码,能设计出4个极点0个零点的IIR优化滤波器

function f = stepresp(x, a, b, c,d,M1)
%STEPRESP computes the step response of an analog filter with any number of pole pairs.
%
%	This function takes four arguments:
%	  x is time
%	  a are the real values of the poles
%	  b are imaginary values of the poles
%	  c are the real values of the zeros
%	  c are imaginary values of the zeros
%	  M1 scales the step response
expr1 = b(1).^(-1);
expr2 = a(2).^2 + b(2).^2;
expr3 = ((a(1) - a(2)).^2 + (b(1) - b(2)).^2).*((a(1) - a(2)).^2 + (b(1) + b(2)).^2);
expr4 = -1./2;
expr5 = b(1).*cos(angle(1 + (i.*(b(1) - b(2)))./(a(1) - a(2))) + angle(1 + (i.*(b(1) + b(2)))./(a(1) - a(2))));
expr6 = a(1).*sin(angle(1 + (i.*(b(1) - b(2)))./(a(1) - a(2))) + angle(1 + (i.*(b(1) + b(2)))./(a(1) - a(2))));
expr7 = exp(x.*a(1));
expr8 = cos(x.*b(1));
expr9 = a(1);
expr10 = a(1).^2 + b(1).^2;
expr11 = sin(angle(1 + (i.*(b(1) - b(2)))./(a(1) - a(2))) + angle(1 + (i.*(b(1) + b(2)))./(a(1) - a(2))));
expr12 = sin(x.*b(1));
expr13 = b(2).^(-1);
expr14 = ((-a(1) + a(2)).^2 + (-b(1) + b(2)).^2).*((-a(1) + a(2)).^2 + (b(1) + b(2)).^2);
expr15 = b(2).*cos(angle(1 + (i.*(-b(1) + b(2)))./(-a(1) + a(2))) + angle(1 + (i.*(b(1) + b(2)))./(-a(1) + a(2))));
expr16 = a(2).*sin(angle(1 + (i.*(-b(1) + b(2)))./(-a(1) + a(2))) + angle(1 + (i.*(b(1) + b(2)))./(-a(1) + a(2))));
expr17 = exp(x.*a(2));
expr18 = cos(x.*b(2));
expr19 = a(2);
expr20 = sin(angle(1 + (i.*(-b(1) + b(2)))./(-a(1) + a(2))) + angle(1 + (i.*(b(1) + b(2)))./(-a(1) + a(2))));
expr21 = sin(x.*b(2));
expr22 = expr10.*expr13.*expr14.^expr4.*(expr15 + expr16).*(1 - expr17.*(expr18 - expr13.*(expr19 - (expr2.*expr20)./(expr15 + expr16)).*expr21));
expr23 = expr1.*expr2.*expr3.^expr4.*(expr5 + expr6).*(1 - expr7.*(expr8 - expr1.*expr12.*(-((expr10.*expr11)./(expr5 + expr6)) + expr9)));
expr24 = expr22 + expr23;
f = M1.*expr24;
end