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.