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bundles / scipy 1.17.1 / scipy / signal / _filter_design / tf2sos

function

scipy.signal._filter_design:tf2sos

source: /scipy/signal/_filter_design.py :1312

Signature

def   tf2sos ( b ,  a ,  pairing = None ,  * ,  analog = False )

Summary

Return second-order sections from transfer function representation

Parameters

b : array_like

Numerator polynomial coefficients.

a : array_like

Denominator polynomial coefficients.

pairing : {None, 'nearest', 'keep_odd', 'minimal'}, optional

The method to use to combine pairs of poles and zeros into sections. See zpk2sos for information and restrictions on pairing and analog arguments.

analog : bool, optional

If True, system is analog, otherwise discrete.

Returns

sos : ndarray

Array of second-order filter coefficients, with shape (n_sections, 6). See sosfilt for the SOS filter format specification.

Notes

It is generally discouraged to convert from TF to SOS format, since doing so usually will not improve numerical precision errors. Instead, consider designing filters in ZPK format and converting directly to SOS. TF is converted to SOS by first converting to ZPK format, then converting ZPK to SOS.

Array API Standard Support

tf2sos 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                   ⚠️ no JIT             ⛔                   
Dask                  ⚠️ computes graph     n/a                 
====================  ====================  ====================

See dev-arrayapi for more information.

Examples

Find the 'sos' (second-order sections) of the transfer function H(s) using its polynomial representation. .. math:: H(s) = \frac{s^2 - 3.5s - 2}{s^4 + 3s^3 - 15s^2 - 19s + 30} 
from scipy.signal import tf2sos
tf2sos([1, -3.5, -2], [1, 3, -15, -19, 30], analog=True)
✓

See also

sosfilt
zpk2sos

Aliases

  • scipy.signal.tf2sos

Referenced by

This package