def _invtransparams(self, start_params):
        """
        Inverse of the Jones reparameterization
        """
        k_ar, k_ma = self.k_ar, self.k_ma
        k = self.k_exog + self.k_trend
        newparams = start_params.copy()
        arcoefs = newparams[k:k+k_ar]
        macoefs = newparams[k+k_ar:]
        # AR coeffs
        if k_ar != 0:
            newparams[k:k+k_ar] = _ar_invtransparams(arcoefs)

        # MA coeffs
        if k_ma != 0:
            newparams[k+k_ar:k+k_ar+k_ma] = _ma_invtransparams(macoefs)
        return newparams
dataset/ETHPy150Open statsmodels/statsmodels/statsmodels/tsa/arima_model.py/ARMA._invtransparams/original