Return density from p, s, and X or Xi
function density_psX extends Modelica.Icons.Function; input AbsolutePressure p "Pressure"; input SpecificEntropy s "Specific entropy"; input MassFraction X[:] "Mass fractions"; input FixedPhase phase = 0 "2 for two-phase, 1 for one-phase, 0 if not known"; output Density d "Density"; end density_psX;