`scipy.signal._filter_design:sos2tf`

Signature

def sos2tf(sos)

Return a single transfer function from a series of second-order sections.

sos : array_like: Array of second-order filter coefficients, must have shape (n_sections, 6). See sosfilt for the SOS filter format specification.

Find the polynomial representation of an elliptic filter using its 'sos' (second-order sections) format.

from scipy.signal import sos2tf
from scipy import signal
sos = signal.ellip(1, 0.001, 50, 0.1, output='sos')

✓

sos2tf(sos)

✗

(array([0.91, 0.91, 0.  ]), array([1.  , 0.83, 0.  ]))