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scipy.signal.cheb1ord

scipy.signal.cheb1ord(wp, ws, gpass, gstop, analog=0)

Chebyshev type I filter order selection.

Return the order of the lowest order digital Chebyshev Type I filter that loses no more than gpass dB in the passband and has at least gstop dB attenuation in the stopband.

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

Non-zero to design an analog filter (in this case wp and ws are in radians / second).

Returns :

ord : int

The lowest order for a Chebyshev type I filter that meets specs.

wn : ndarray or float

The Chebyshev natural frequency (the “3dB frequency”) for use with cheby1 to give filter results.