Parameters :  wp, ws : float
Passband and stopband edge frequencies, normalized from 0 to 1 (1
corresponds to pi radians / sample). For example:
 Lowpass: wp = 0.2, ws = 0.3
 Highpass: wp = 0.3, ws = 0.2
 Bandpass: wp = [0.2, 0.5], ws = [0.1, 0.6]
 Bandstop: wp = [0.1, 0.6], ws = [0.2, 0.5]
gpass : float
The maximum loss in the passband (dB).
gstop : float
The minimum attenuation in the stopband (dB).
analog : int, optional
Nonzero to design an analog filter (in this case wp and ws are in
radians / second).
Returns :
—— :
ord : int
The lowest order for an Elliptic (Cauer) filter that meets specs.
wn : ndarray or float
The Chebyshev natural frequency (the “3dB frequency”) for use with
ellip to give filter results.
