scipy.signal.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.
New 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)