def butter_lp(n, Wn):
 zeros = []
 poles = _butter_analog_poles(n)
 k = 1
 fs = 2
 warped = ((2 * fs) * mpmath.tan(((mpmath.pi * Wn) / fs)))
 (z, p, k) = _zpklp2lp(zeros, poles, k, wo=warped)
 (z, p, k) = _zpkbilinear(z, p, k, fs=fs)
 return (z, p, k)

def butter_lp ( n , Wn ) : zeros = [ ] poles = _butter_analog_poles ( n ) k = 1 fs = 2 warped = ( ( 2 * fs ) * mpmath . tan ( ( ( mpmath . pi * Wn ) / fs ) ) ) ( z , p , k ) = _zpklp2lp ( zeros , poles , k , wo = warped ) ( z , p , k ) = _zpkbilinear ( z , p , k , fs = fs ) return ( z , p , k )
lowpass butterworth digital filter design .