Central moment of \(y_n\) with order \(l\)
l (int) – order of the central moment.
poly with attribute keyfor = (‘(n_1m*k1+n_2m*k2)^{-i_m},…,(n_11*k1+n_21*k2)^{-i_1}’, ‘e^{-(n1*k1+n2*k2)h}’,’h’, ‘theta1’,’sigma_v1’, ‘theta2’,’sigma_v2’).
keyfor
Poly