pyFDN.is_allpass

pyFDN.is_allpass(A, B, C, D, delays, tol=1e-09)

Test whether the delay state-space system is allpass.

Checks that the determinant transfer function has numerator = reversed(denominator) (up to sign). See “Allpass Feedback Delay Networks” by Sebastian J. Schlecht.

Parameters:

• A (ArrayLike) – Delay state-space matrices.

• B (ArrayLike) – Delay state-space matrices.

• C (ArrayLike) – Delay state-space matrices.

• D (ArrayLike) – Delay state-space matrices.

• delays (ArrayLike) – Delay lengths (samples), length N.

• tol (float) – Tolerance for coefficient comparison.

Return type:

tuple[bool, ndarray, ndarray]

Returns:

• is_a (bool) – True if allpass.

• den (ndarray) – Denominator polynomial (z^{-1} ordering).

• num (ndarray) – Numerator polynomial (z^{-1} ordering).