Function rho = mollier_rho(T,X,pb,prop); returns the density rho of the air mixture in kg per m3 for the given air temperature T (in degrees centigrade), absolute humidity X of the air (in kg of water vapour per kg of dry air, and total pressure (or barometric pressure) pb (in Pa). The fourth input argument prop is a struct containing information on humid air properties, as returned by m-file mollier_humidairprop.m. This function is called, if the fourth input argument is not given. If the third input argument pb is empty or not given, the value of prop.pbstandard is used. The calculation of the air mixture density is based on a reference density or dry air prop.rhoref, at temperature prop.Tref and total pressure prop.pref. (c) 2026 fabien van mook 2026.08.20 release of this file within package "fvm-mollier" under GNU GPLv3+