covariance & localisation: extract functions

[mathause]

train_lv_find_localized_ecov finds the optimal localization radius for the empirical covariance matrix and derives the empirical cov matrix.

mesmer/mesmer/calibrate_mesmer/train_lv.py

Line 273 in 3892e76

def train_lv_find_localized_ecov(y, wgt_scen_eq, aux, cfg):

The statistical methods should be extracted.