function Density_derh_Ph input Units.SI.AbsolutePressure P "Pressure (Pa)"; input Units.SI.SpecificEnthalpy h "Specific enthalpy"; input Integer fluid "<html>Fluid number: <br>1 - Water/Steam <br>2 - C3H3F5 <br>3 - FlueGases <br>4 - MoltenSalt <br>5 - Oil <br>6 - DryAirIdealGas <br>7 - WaterSteamSimple </html>"; input Integer mode "IF97 region - 0:automatic computation"; input Real Xco2 "CO2 mass fraction"; input Real Xh2o "H2O mass fraction"; input Real Xo2 "O2 mass fraction"; input Real Xso2 "SO2 mass fraction"; output Units.SI.DerDensityByEnthalpy ddhp "density derivative by enthalpy"; end Density_derh_Ph;