Skip to main content
`Ctrl`+`K`
scipy.signal.

# symiirorder2

scipy.signal.symiirorder2(input, r, omega, precision=-1.0)

  Implement a smoothing IIR filter with mirror-symmetric boundary conditions using a cascade of second-order sections.

  The second section uses a reversed sequence. This implements the following transfer function:

                               cs^2
      H(z) = ---------------------------------------
             (1 - a2/z - a3/z^2) (1 - a2 z - a3 z^2 )

  where:

      a2 = 2 * r * cos(omega)
      a3 = - r ** 2
      cs = 1 - 2 * r * cos(omega) + r ** 2

  Parameters:
    inputndarray

      The input signal.

    r, omegafloat

      Parameters in the transfer function.

    precisionfloat

      Specifies the precision for calculating initial conditions of the recursive filter based on mirror-symmetric input.

  Returns:
    outputndarray

      The filtered signal.