Compute density as function of pressure, temperature and composition
function d_pTX input Modelica.SIunits.AbsolutePressure p "Pressure"; input Modelica.SIunits.Temperature T "Temperature"; input Modelica.SIunits.MassFraction X[:] "Mass fractions "; output Modelica.SIunits.Density d "Density"; end d_pTX;