Log-likelihood of the multinomial logit model for each observation.
Parameters : | params : array-like
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Returns : | loglike : ndarray (nobs,)
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Notes
\ln L_{i}=\sum_{j=0}^{J}d_{ij}\ln\left(\frac{\exp\left(\beta_{j}^{\prime}x_{i}\right)}{\sum_{k=0}^{J}\exp\left(\beta_{k}^{\prime}x_{i}\right)}\right)
for observations i=1,...,n
where d_{ij}=1 if individual i chose alternative j and 0 if not.