statsmodels.robust.norms.MQuantileNorm.psi_deriv#
- MQuantileNorm.psi_deriv(z)[source]#
The derivative of MQuantileNorm function
- Parameters:
- zarray_like
1d array
- Returns:
- psi_deriv
ndarray The value of the derivative of the psi function.
- psi_deriv
Notes
Used to estimate the robust covariance matrix.