def numerical_distance(impedance, angle, distance, wavenumber):
    return np.sqrt(-1j*wavenumber*distance*(1.0 + 1.0/impedance * np.cos(angle) - np.sqrt(1.0-(1.0/impedance)**2.0)*np.sin(angle)))
Numerical distance :math:`w`.
dataset/ETHPy150Open python-acoustics/python-acoustics/acoustics/reflection.py/numerical_distance