RamsayE.
rho
The robust criterion function for Ramsay’s Ea.
z : array-like
1d array
rho : array
rho(z) = a**-2 * (1 - exp(-a*|z|)*(1 + a*|z|))
statsmodels.robust.norms.RamsayE.psi_deriv
statsmodels.robust.norms.RamsayE.weights