function density_derT_p_phX input Modelica.SIunits.AbsolutePressure p "pressure"; input Modelica.SIunits.SpecificEnthalpy h "specific enthalpy"; input Modelica.SIunits.MassFraction X[nC] = reference_X "Mass fraction"; input Properties state; output Real ddTp "Density derivative wrt T at constant pressure"; end density_derT_p_phX;