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# scipy.signal.freqz

`scipy.signal.``freqz`(b, a=1, worN=None, whole=0, plot=None)

  Compute frequency response of a digital filter.

  Given the numerator (b) and denominator (a) of a digital filter compute its frequency response.

  > > > jw -jw -jmw

  > > jw B(e) b[0] + b[1]e + .... + b[m]e

  > H(e) = —- = ————————————

  >   > jw -jw -jnw

  >   A(e) a[0] + a[2]e + .... + a[n]e

  Parameters: | b : ndarray numerator of a linear filter a : ndarray numerator of a linear filter worN : {None, int}, optional If None, then compute at 200 frequencies around the interesting parts of the response curve (determined by pole-zero locations). If a single integer, the compute at that many frequencies. Otherwise, compute the response at frequencies given in worN. whole : {0,1}, optional Normally, frequencies are computed from 0 to pi (upper-half of unit-circle. If whole is non-zero compute frequencies from 0 to 2*pi.
  Returns: | w : ndarray The frequencies at which h was computed. h : ndarray The frequency response.

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