density derivative by specific enthalpy
function ddhp_props 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"; output Units.SI.DerDensityByEnthalpy ddhp "density derivative by specific enthalpy"; end ddhp_props;