function rho_ph_dd
extends Modelica.Icons.Function;
input Units.SI.Pressure p "pressure";
input Units.SI.SpecificEnthalpy h "specific enthalpy";
input ThermoSysPro.Properties.WaterSteam.Common.IF97TwoPhaseAnalytic aux "auxiliary record";
input Real p_d "derivative of pressure";
input Real h_d "derivative of specific enthalpy";
input Real p_dd "second derivative of pressure";
input Real h_dd "second derivative of specific enthalpy";
output Real rho_dd "Second derivative of density";
end rho_ph_dd;