using uCalcSoftware;

var uc = new uCalc();
// By default, invalid operations return 'nan'
Console.WriteLine(uc.EvalStr("sqrt(-1)"));

// Enable error raising for this specific case
uc.Error.TrapOnInvalid = true;

// Now, the same operation returns a descriptive error message
Console.WriteLine(uc.EvalStr("sqrt(-1)"));