`scipy.signal._filter_design:band_stop_obj`

source: /scipy/signal/_filter_design.py :4054

Signature

   def     band_stop_obj (    wp    ,    ind    ,    passb    ,    stopb    ,    gpass    ,    gstop    ,    type      )

Summary

Band Stop Objective Function for order minimization.

Extended Summary

Returns the non-integer order for an analog band stop filter.

Parameters

wp : scalar: Edge of passband passb.
ind : int, {0, 1}: Index specifying which passb edge to vary (0 or 1).
passb : ndarray: Two element sequence of fixed passband edges.
stopb : ndarray: Two element sequence of fixed stopband edges.
gstop : float: Amount of attenuation in stopband in dB.
gpass : float: Amount of ripple in the passband in dB.
type : {'butter', 'cheby', 'ellip'}: Type of filter.

Returns

n : scalar: Filter order (possibly non-integer).

Notes

Band-stop filters are used in applications where certain frequency components need to be blocked while others are allowed; for instance, removing noise at specific frequencies while allowing the desired signal to pass through. The order of a filter often determines its complexity and accuracy. Determining the right order can be a challenge. This function aims to provide an appropriate order for an analog band stop filter.

Array API Standard Support

band_stop_obj has experimental support for Python Array API Standard compatible backends in addition to NumPy. Please consider testing these features by setting an environment variable SCIPY_ARRAY_API=1 and providing CuPy, PyTorch, JAX, or Dask arrays as array arguments. The following combinations of backend and device (or other capability) are supported.

====================  ====================  ====================
Library               CPU                   GPU
====================  ====================  ====================
NumPy                 ✅                     n/a                 
CuPy                  n/a                   ⛔                   
PyTorch               ⛔                     ⛔                   
JAX                   ⛔                     ⛔                   
Dask                  ⛔                     n/a                 
====================  ====================  ====================

See dev-arrayapi for more information.

Examples

import numpy as np
from scipy.signal import band_stop_obj
wp = 2
ind = 1
passb = np.array([1, 3])
stopb = np.array([0.5, 4])
gstop = 30
gpass = 3
filter_type = 'butter'
band_stop_obj(wp, ind, passb, stopb, gpass, gstop, filter_type)

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Aliases

scipy.signal.band_stop_obj