Derivative function of rho_ph
function rho_ph_der extends Modelica.Icons.Function; input SI.Pressure p "Pressure"; input SI.SpecificEnthalpy h "Specific enthalpy"; input Common.IF97BaseTwoPhase properties "Auxiliary record"; input Real p_der "Derivative of pressure"; input Real h_der "Derivative of specific enthalpy"; output Real rho_der "Derivative of density"; end rho_ph_der;