lp2hp_zpk#
- scipy.signal.lp2hp_zpk(z, p, k, wo=1.0)[source]#
- Transform a lowpass filter prototype to a highpass filter. - Return an analog high-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 high-pass filter transfer function. 
- pndarray
- Poles of the transformed high-pass filter transfer function. 
- kfloat
- System gain of the transformed high-pass filter. 
 
 - Notes - This is derived from the s-plane substitution \[s \rightarrow \frac{\omega_0}{s}\]- This maintains symmetry of the lowpass and highpass responses on a logarithmic scale. - Added in version 1.1.0. - Examples - Use the ‘zpk’ (Zero-Pole-Gain) representation of a lowpass filter to transform it to a highpass filter with a cutoff frequency wo. - >>> from scipy.signal import lp2hp_zpk >>> z = [ -2 + 3j , -0.5 - 0.8j ] >>> p = [ -1 , -4 ] >>> k = 10 >>> wo = 0.6 >>> lp2hp_zpk(z, p, k, wo) ( array([-0.09230769-0.13846154j, -0.33707865+0.53932584j]), array([-0.6 , -0.15]), 8.5)