Integrated Expected Improvement

def _compute_acq(self,x):
        """
        Integrated Expected Improvement
        """
        means, stds = self.model.predict(x)
        fmins = self.model.get_fmin()
        f_acqu = 0
        for m,s,fmin in zip(means, stds, fmins):
            _, Phi, _ = get_quantiles(self.jitter, fmin, m, s)
            f_acqu += Phi
        return f_acqu/len(means)