function s_dTX_der extends Modelica.Icons.UnderConstruction; input SI.Density d "Density"; input SI.Temperature T "Temperature"; input SI.MassFraction X[:] "Mass fractions of moist air"; input Real dd(unit = "kg/(m3.s)") "Derivative of density"; input Real dT(unit = "K/s") "Derivative of temperature"; input Real dX[nX](each unit = "1/s") "Derivative of mass fractions"; output Real ds(unit = "J/(kg.K.s)") "Specific entropy at p, T, X"; end s_dTX_der;