def _transparams(self, params):
        """
        Transforms params to induce stationarity/invertability.

        Reference
        ---------
        Jones(1980)
        """
        k_ar, k_ma = self.k_ar, self.k_ma
        k = self.k_exog + self.k_trend
        newparams = np.zeros_like(params)

        # just copy exogenous parameters
        if k != 0:
            newparams[:k] = params[:k]

        # AR Coeffs
        if k_ar != 0:
            newparams[k:k+k_ar] = _ar_transparams(params[k:k+k_ar].copy())

        # MA Coeffs
        if k_ma != 0:
            newparams[k+k_ar:] = _ma_transparams(params[k+k_ar:].copy())
        return newparams
dataset/ETHPy150Open statsmodels/statsmodels/statsmodels/tsa/arima_model.py/ARMA._transparams/original