import("stdfaust.lib");
import("filters.lib");

biquad(a1,a2,b0,b1,b2) = + ~ conv2(a1,a2) : conv3(b0,b1,b2)
  with{
    conv3(k0,k1,k2,x) = k0*x + k1*x'+ k2*x'';
    conv2(k0,k1,x) = k0*x + k1*x';
  };

f1 = biquad(-0.02569, 0.260502, -0.260502, 0.02569, 1) : biquad(1.8685, -0.870686, 0.870686, -1.8685, 1) ;
f2 = biquad(1.94632, -0.94657, 0.94657, -1.94632, 1) : biquad(0.83774, -0.06338, 0.06338, -0.83774, 1) ;

hilbert = f1, f2; // f1 advanced 90° - f2 delayed 90°

process = hilbert;