Total derivative of density_ph
function density_ph_der extends Modelica.Icons.Function; input AbsolutePressure p "Pressure"; input SpecificEnthalpy h "Specific enthalpy"; input ThermodynamicState state; input Real p_der "time derivative of pressure"; input Real h_der "time derivative of specific enthalpy"; output Real d_der "time derivative of density"; end density_ph_der;