statsmodels.robust.norms.TukeyBiweight.psi¶
-
TukeyBiweight.
psi
(z)[source]¶ The psi function for Tukey’s biweight estimator
The analytic derivative of rho
- Parameters
- zarray_like
1d array
- Returns
- psi
ndarray
psi(z) = z*(1 - (z/c)**2)**2 for |z| <= R
psi(z) = 0 for |z| > R
- psi