function fresp = frespF1(f1,f,phi)%frespF1(f1,f)	Plot/calculate the frequency response of the F1 filter %in a Saramaki HBF at the points given in the optional f (n by 1) vector.if nargin < 3    phi = 1;    if nargin < 2	f = linspace(0,0.5);    endendcos_w = cos(2*pi*f)';F1 = 0.5;for i = 1:length(f1);    F1 = F1 + f1(i)*((cos_w/phi).^(2*i-1));endif nargout == 0    plot(f,dbv(F1))    grid onelse    fresp = F1;end