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 \[s \rightarrow \frac{s}{\omega_0}\]- Added 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)