return the current region (valid values: 1,2,3,4,5) in IF97, given density and temperature
function region_dT extends Modelica.Icons.Function; input SI.Density d "density"; input SI.Temperature T "temperature (K)"; input Integer phase = 0 "phase: 2 for two-phase, 1 for one phase, 0 if not known"; input Integer mode = 0 "mode: 0 means check, otherwise assume region=mode"; output Integer region "(valid values: 1,2,3,4,5) in IF97"; end region_dT;