scipy.signal.lp2lp_zpk#
- scipy.signal.lp2lp_zpk(z, p, k, wo=1.0)[source]#
Transform a lowpass filter prototype to a different frequency.
Return an analog low-pass filter with cutoff frequency wo from an analog low-pass filter prototype with unity cutoff frequency, using zeros, poles, and gain (‘zpk’) representation.
- Parameters:
- zarray_like
Zeros of the analog filter transfer function.
- parray_like
Poles of the analog filter transfer function.
- kfloat
System gain of the analog filter transfer function.
- wofloat
Desired cutoff, as angular frequency (e.g., rad/s). Defaults to no change.
- Returns:
- zndarray
Zeros of the transformed low-pass filter transfer function.
- pndarray
Poles of the transformed low-pass filter transfer function.
- kfloat
System gain of the transformed low-pass filter.
Notes
This is derived from the s-plane substitution
\[s \rightarrow \frac{s}{\omega_0}\]New in version 1.1.0.
Examples
Use the ‘zpk’ (Zero-Pole-Gain) representation of a lowpass filter to transform it to a new ‘zpk’ representation associated with a cutoff frequency wo.
>>> from scipy.signal import lp2lp_zpk >>> z = [7, 2] >>> p = [5, 13] >>> k = 0.8 >>> wo = 0.4 >>> lp2lp_zpk(z, p, k, wo) ( array([2.8, 0.8]), array([2. , 5.2]), 0.8)