Returns the location where the posterior mean is takes its minimal value.

def get_fmin(self):
        """
        Returns the location where the posterior mean is takes its minimal value.
        """
        ps = self.model.param_array.copy()
        fmins = []
        for s in self.hmc_samples:
            if self.model._fixes_ is None:
                self.model[:] = s
            else:
                self.model[self.model._fixes_] = s
            self.model._trigger_params_changed()
            fmins.append(self.model.predict(self.model.X)[0].min())
        self.model.param_array[:] = ps
        self.model._trigger_params_changed()

        return fmins