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bundles / scipy latest / scipy / signal / _filter_design / freqs_zpk

function

scipy.signal._filter_design:freqs_zpk

source: build-install/usr/lib/python3.14/site-packages/scipy/signal/_filter_design.py:256

Signature

def freqs_zpk(z, p, k, worN = 200)

Summary

Compute frequency response of analog filter.

Extended Summary

Given the zeros z, poles p, and gain k of a filter, compute its frequency response 

           (jw-z[0]) * (jw-z[1]) * ... * (jw-z[-1])
H(w) = k * ----------------------------------------
           (jw-p[0]) * (jw-p[1]) * ... * (jw-p[-1])

Parameters

z : array_like

Zeroes of a linear filter

p : array_like

Poles of a linear filter

k : scalar

Gain of a linear filter

worN : {None, int, array_like}, 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, then compute at that many frequencies. Otherwise, compute the response at the angular frequencies (e.g., rad/s) given in worN.

Returns

w : ndarray

The angular frequencies at which h was computed.

h : ndarray

The frequency response.

Notes

Examples

import numpy as np
from scipy.signal import freqs_zpk, iirfilter
✓
z, p, k = iirfilter(4, [1, 10], 1, 60, analog=True, ftype='cheby1',
                    output='zpk')
✓
w, h = freqs_zpk(z, p, k, worN=np.logspace(-1, 2, 1000))
✓
import matplotlib.pyplot as plt
✓
plt.semilogx(w, 20 * np.log10(abs(h)))
plt.xlabel('Frequency [rad/s]')
plt.ylabel('Amplitude response [dB]')
✗
Text(0, 0.5, 'Amplitude response [dB]')

plt.grid(True)
plt.show()
✓
fig-99e477700239ab7d.png

See also

freqs

Compute the frequency response of an analog filter in TF form

freqz

Compute the frequency response of a digital filter in TF form

freqz_zpk

Compute the frequency response of a digital filter in ZPK form

Aliases

  • scipy.signal.freqs_zpk