scipy.signal.

band_stop_obj#

scipy.signal.band_stop_obj(wp, ind, passb, stopb, gpass, gstop, type)[source]#

Band Stop Objective Function for order minimization.

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

Parameters:

wpscalar: Edge of passband passb.
indint, {0, 1}: Index specifying which passb edge to vary (0 or 1).
passbndarray: Two element sequence of fixed passband edges.
stopbndarray: Two element sequence of fixed stopband edges.
gstopfloat: Amount of attenuation in stopband in dB.
gpassfloat: Amount of ripple in the passband in dB.
type{‘butter’, ‘cheby’, ‘ellip’}: Type of filter.

Returns:

nscalar: 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 Support for the array API standard 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)
np.float64(-2.758504160760643)