public void ClearHistory()
 {
     leftHandSide    = 0;
     rightHandSide   = float.PositiveInfinity;
     calculatedValue = float.PositiveInfinity;
     currentFunction = FunctionalButton.Function.None;
 }
 public void SetFunction(FunctionalButton.Function _function)
 {
     currentFunction = _function;
     rightHandSide   = 0;
 }