Converts mixing ratio x in c1 - c2 tie line to that in
        comp1 - comp2 tie line.

        Args:
            x (float): Mixing ratio x in c1 - c2 tie line, a float between
                0 and 1.
            factor1 (float): Compositional ratio between composition c1 and
                processed composition comp1. E.g., factor for
                Composition('SiO2') and Composition('O') is 2.
            factor2 (float): Compositional ratio between composition c2 and
                processed composition comp2.

        Returns:
            Mixing ratio in comp1 - comp2 tie line, a float between 0 and 1.

def _reverse_convert(x, factor1, factor2):
        """
        Converts mixing ratio x in c1 - c2 tie line to that in
        comp1 - comp2 tie line.

        Args:
            x (float): Mixing ratio x in c1 - c2 tie line, a float between
                0 and 1.
            factor1 (float): Compositional ratio between composition c1 and
                processed composition comp1. E.g., factor for
                Composition('SiO2') and Composition('O') is 2.
            factor2 (float): Compositional ratio between composition c2 and
                processed composition comp2.

        Returns:
            Mixing ratio in comp1 - comp2 tie line, a float between 0 and 1.
        """
        return x * factor1 / ((1-x) * factor2 + x * factor1)