pyFDN.adj_poly

pyFDN.adj_poly(polynomial_matrix, var='z^1', tol=-200.0)

Adjugate of a polynomial matrix via FFT evaluation.

Evaluates the matrix at N * L DFT points, takes the scalar adjugate() at every bin, and transforms back (approach of Henrion, Hromcik & Sebek 2000; translates adjPoly.m).

Parameters:

• polynomial_matrix (array) – Polynomial matrix of shape (N, N, L).

• var (str) – Coefficient convention along axis 2: "z^1" — descending powers of z, last slice = z^0 (the loop_tf() convention); "z^-1" — ascending powers of z^{-1}, first slice = z^0 (the pyFDN convention used by det_polynomial()).

• tol (float) – Noise floor in dB (relative to each entry’s maximum) used to trim the result to its actual degree.

Returns:

adj – Adjugate polynomial matrix (N, N, degree + 1) in the same convention as the input.

Return type:

ndarray