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# scipy.signal.sos2tf

scipy.signal.sos2tf(sos)

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

  Parameters:
    sos array_like

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

  Returns:
    b ndarray

      Numerator polynomial coefficients.

    a ndarray

      Denominator polynomial coefficients.

  Notes

  New in version 0.16.0.

  Examples

  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([0.91256522, 0.91256522, 0.        ]),
          array([1.        , 0.82513043, 0.        ]))