$//<![CDATA[ \begin{array}{l}\displaystyle \mu_{od}(T) = \left( c_1 + c_2 \, \gamma_{API}^{c_3} \right) \left( \frac{c_4}{T+c_5} \right)^X\end{array} //]]>$
$//<![CDATA[ \begin{array}{l}\log_{10} X = c_6 + \frac{c_7}{\gamma_{API}}\end{array} //]]>$
$//<![CDATA[ \begin{array}{l}c_1 = 0.32, \ c_2 = 1.8 \cdot 10^7, \ c_3 = - 4.53, \ c_4 =360, \ c_5 = -260, \ c_6 = 0.43, \ c_7 = 8.33\end{array} //]]>$