Return the current region (valid values: 1,2,3,5) in IF97, given pressure and temperature
function region_pT extends Modelica.Icons.Function; input SI.Pressure p "Pressure"; input SI.Temperature T "Temperature (K)"; input Integer mode = 0 "Mode: 0 means check, otherwise assume region=mode"; output Integer region "Region (valid values: 1,2,3,5) in IF97, region 4 is impossible!"; end region_pT;