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;
.ThermoSysPro.Properties.Fluid.Density_derh_Ph