statsmodels.robust.norms.AndrewWave.psi¶
-
AndrewWave.
psi
(z)[source]¶ The psi function for Andrew’s wave
The analytic derivative of rho
- Parameters
- zarray_like
1d array
- Returns
- psi
ndarray
psi(z) = sin(z/a) for |z| <= a*pi
psi(z) = 0 for |z| > a*pi
- psi