private List <EquationComponent> ParseExpression(string expression)
{
List <EquationComponent> result = new List <EquationComponent>();
string currentValue = string.Empty;
string currentFunction = string.Empty;
char last = ' ';
for (int i = 0; i < expression.Length; i++)
{
char c = expression[i];
if (char.IsNumber(c) || c == '.' || c == 'e' || (last == 'e' && (c == '-' || c == '+')))
{
currentValue += c;
}
else if (char.IsLetter(c))
{
currentFunction += c;
}
else
{
if (currentValue != string.Empty)
{
result.Add(new EquationComponent(Precedence.Number, currentValue));
}
if (currentFunction != string.Empty)
{
result.Add(new EquationComponent(Precedence.Function, currentFunction.ToLower()));
}
currentFunction = string.Empty;
currentValue = string.Empty;
if (c != ' ')
{
Precedence previous = Precedence.None;
if (result.Count > 0)
{
previous = result.Last().ComponentType;
}
Precedence currentPrecedence = EquationComponent.GetComponentType(c.ToString(), previous);
if (currentPrecedence == Precedence.Negation && previous == Precedence.Negation)
{
result.Remove(result.Last());
if (result.Last().Component != "+")
{
result.Add(new EquationComponent(Precedence.AdditionSubtraction, "+"));
}
}
else
{
result.Add(new EquationComponent(currentPrecedence, c.ToString()));
}
}
}
last = c;
}
if (currentValue != string.Empty)
{
result.Add(new EquationComponent(Precedence.Number, currentValue));
}
if (currentFunction != string.Empty)
{
result.Add(new EquationComponent(Precedence.Function, currentFunction.ToLower()));
}
return(result);
}
private double PerformOperation(Stack <double> operands, EquationComponent item)
{
double op2 = 0;
double op1 = 0;
switch (item.Component)
{
case "&":
op2 = operands.Pop();
op1 = operands.Pop();
return(Math.Pow(op1, op2));
case "*":
op2 = operands.Pop();
op1 = operands.Pop();
return(op1 * op2);
case "/":
op2 = operands.Pop();
op1 = operands.Pop();
return(op1 / op2);
case "+":
op2 = operands.Pop();
op1 = operands.Pop();
return(op1 + op2);
case "-":
if (item.ComponentType == Precedence.Negation)
{
op1 = operands.Pop();
return(op1 * -1);
}
else
{
op2 = operands.Pop();
op1 = operands.Pop();
return(op1 - op2);
}
case "log":
op1 = operands.Pop();
return(Math.Log(op1));
case "ln":
op1 = operands.Pop();
return(Math.Log(op1));
case "exp":
op1 = operands.Pop();
return(Math.Exp(op1));
case "sqrt":
op1 = operands.Pop();
return(Math.Sqrt(op1));
case "abs":
op1 = operands.Pop();
return(Math.Abs(op1));
case "atan":
op1 = operands.Pop();
return(Math.Atan(op1));
case "acos":
op1 = operands.Pop();
return(Math.Acos(op1));
case "asin":
op1 = operands.Pop();
return(Math.Asin(op1));
case "sinh":
op1 = operands.Pop();
return(Math.Sinh(op1));
case "cosh":
op1 = operands.Pop();
return(Math.Cosh(op1));
case "tanh":
op1 = operands.Pop();
return(Math.Tanh(op1));
case "tan":
op1 = operands.Pop();
return(Math.Tan(op1));
case "sin":
op1 = operands.Pop();
return(Math.Sin(op1));
case "cos":
op1 = operands.Pop();
return(Math.Cos(op1));
}
return(double.NaN);
}
