bundles / scipy latest / scipy / signal / _filter_design / lp2bs_zpk
function
scipy.signal._filter_design:lp2bs_zpk
source: build-install/usr/lib/python3.14/site-packages/scipy/signal/_filter_design.py:3301
Signature
def lp2bs_zpk(z, p, k, wo = 1.0, bw = 1.0)Summary
Transform a lowpass filter prototype to a bandstop filter.
Extended Summary
Return an analog band-stop filter with center frequency wo and stopband width bw from an analog low-pass filter prototype with unity cutoff frequency, using zeros, poles, and gain ('zpk') representation.
Parameters
z: array_likeZeros of the analog filter transfer function.
p: array_likePoles of the analog filter transfer function.
k: floatSystem gain of the analog filter transfer function.
wo: floatDesired stopband center, as angular frequency (e.g., rad/s). Defaults to no change.
bw: floatDesired stopband width, as angular frequency (e.g., rad/s). Defaults to 1.
Returns
z: ndarrayZeros of the transformed band-stop filter transfer function.
p: ndarrayPoles of the transformed band-stop filter transfer function.
k: floatSystem gain of the transformed band-stop filter.
Notes
This is derived from the s-plane substitution
This is the "wideband" transformation, producing a stopband with geometric (log frequency) symmetry about wo.
Examples
Transform a low-pass filter represented in 'zpk' (Zero-Pole-Gain) form into a bandstop filter represented in 'zpk' form, with a center frequency wo and bandwidth bw.from scipy.signal import lp2bs_zpk z = [ ] p = [ 0.7 , -1 ] k = 9 wo = 0.5 bw = 10✓
lp2bs_zpk(z, p, k, wo, bw)
✗(array([ 0.+0.5j, 0.+0.5j, -0.-0.5j, -0.-0.5j]), array([14.2681928 +0.j, -0.02506281+0.j, 0.01752149+0.j, -9.97493719+0.j]), np.float64(-12.857142857142858))
See also
Aliases
scipy.signal.lp2bs_zpk