def METHOD_NAME(epsr, sig, fc):
    """Compute attenuation factor"""
    eps = epsr * 8.854e-12
    # sig = 10**logsig
    mu = 4 * np.pi * 1e-7
    w = 2 * np.pi * fc
    a = w * np.sqrt(mu * eps / 2) * np.sqrt(np.sqrt(1 + (sig / (w * eps)) ** 2) - 1)
    return a