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# scipy.signal.ellip

`scipy.signal.``ellip`(N, rp, rs, Wn, btype='low', analog=False, output='ba')

  Elliptic (Cauer) digital and analog filter design.

  Design an Nth order digital or analog elliptic filter and return the filter coefficients in (B,A) or (Z,P,K) form.

  Parameters : | N : int The order of the filter. rp : float Provides the maximum ripple in the passband. (dB) rs : float Provides the minimum attenuation in the stop band. (dB) Wn : array_like A scalar or length-2 sequence giving the critical frequencies. For digital filters, Wn is normalized from 0 to 1, where 1 is the Nyquist frequency, pi radians / sample. (Wn is thus in half-cycles / sample.) For analog filters, Wn is in radians / second. btype : {‘lowpass’, ‘highpass’, ‘bandpass’, ‘bandstop’}, optional The type of filter. Default is ‘lowpass’. analog : bool, optional When True, return an analog filter, otherwise a digital filter is returned. output : {‘ba’, ‘zpk’}, optional Type of output: numerator/denominator (‘ba’) or pole-zero (‘zpk’). Default is ‘ba’.
  Returns : | b, a : ndarray, ndarray Numerator (b) and denominator (a) polynomials of the IIR filter. Only returned if `output='ba'`. z, p, k : ndarray, ndarray, float Zeros, poles, and system gain of the IIR filter transfer function. Only returned if `output='zpk'`.

  See also

  `ellipord`

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