public static int region_given_ps(double p, double s)
{
int r = IF97.Region_ps(p / 1000000.0, s / 1000.0);
switch (r)
{
case 1: //liquid
return(0); //subcooled liquid
case 2: //vapor
return(2); //superheated vapor
case 3:
case 4: //two-phase
case 5:
return(1); //two-phase
}
return(-1);
}