code: def log_likelihood(self, ts):
          
          likelihood = self._jmodel.logLikelihood(_py2java(self._ctx, Vectors.dense(ts)))
          return _java2py(self._ctx, likelihood)
docs: Returns the log likelihood of the parameters on the given time series.
          
          Based on http://www.unc.edu/~jbhill/Bollerslev_GARCH_1986.pdf