//check if two string values are equal
public bool isEqual(Token test)
{
if (test.sValue.Equals(this.sValue,StringComparison.OrdinalIgnoreCase) )
if (test.vType == this.vType)
return true;
return false;
}
//get the numeric value the function at x
public double evalFuncAt(double x)
{
if (funcToken == null)
return 0;
//make copy
List<Token> ExprCopy = new List<Token>();
for (int i = 0; i < funcToken.Count; i++)
{
ExprCopy.Add(new Token(funcToken[i].vType, funcToken[i].sValue));
}
//plug in value of x into copy
for (int i = 0; i < ExprCopy.Count; i++)
{
if (ExprCopy[i].vType == ValType.VARIABLE)
{
ExprCopy[i] = new Token(x);
}
}
//evaluate the copy
return eval(ExprCopy);
}
//get numeric value of expression
// assume x is replaced by value
private double eval(List<Token> ExprCopy)
{
//evaluate in order of:
//methods
//brackets
//exponents
//divisions
//multiplications
//additions
//subtractions
//eval methods
for (int i = 0; i < ExprCopy.Count; i++)
{
//if its the start of a method
if (ExprCopy[i].vType == ValType.LETTER)
{
//check if its a constant
if(ExprCopy[i].ToString().Equals("PI"))
{
ExprCopy[i].dValue = Math.PI;
ExprCopy[i].vType = ValType.NUMBER;
}
//find args of method
int bracketDepth = 0;
List<Token> arguments = new List<Token>();
//start args right after method
for (int j = i+1; j < ExprCopy.Count; j++)
{
//check bracket depth
if (ExprCopy[j].sValue.Equals("("))
bracketDepth++;
else if (ExprCopy[j].sValue.Equals(")"))
bracketDepth--;
//put token into arguments and rmv from ExprCopy
arguments.Add(ExprCopy[j]);
ExprCopy.RemoveAt(j);
j--;
if (bracketDepth == 0)
break;
}
//recursively evaluate arguments
double dResult = eval(arguments);
//replace method with numeric value
dResult = mathFuncEval(ExprCopy[i].ToString(),dResult);
ExprCopy[i] = new Token(dResult);
}//end if
}//end methods loop
//eval brackets
for (int i = 0; i < ExprCopy.Count; i++)
{
//if its the start of a bracket
if (ExprCopy[i].vType == ValType.OPBRACKET)
{
//find args of method
int bracketDepth = 0;
List<Token> arguments = new List<Token>();
//start args right after method
for (int j = i+1; j < ExprCopy.Count; j++)
{
//check bracket depth
if (ExprCopy[j].sValue.Equals("("))
bracketDepth++;
else if (ExprCopy[j].sValue.Equals(")"))
bracketDepth--;
//put token into arguments and rmv from ExprCopy
arguments.Add(ExprCopy[j]);
ExprCopy.RemoveAt(j);
j--;
if (bracketDepth == 0)
break;
}
//recursively evaluate arguments
double dResult = eval(arguments);
//replace bracket with numeric value
ExprCopy[i] = new Token(dResult);
}//end if
}//end brackets loop
//exponents loop
for (int i = 0; i < ExprCopy.Count; i++)
{
//if its the start of an exponent
if (ExprCopy[i].ToString().Equals("^"))
{
//replace with value
double x = ExprCopy[i-1].dValue;
double y = ExprCopy[i+1].dValue;
double expRes =System.Math.Pow(x,y);
ExprCopy[i-1] = new Token(expRes);
//remove operator and argument
ExprCopy.RemoveAt(i);
ExprCopy.RemoveAt(i);
i--;
i--;
}
}//end exponents loop
//divisions loop
for (int i = 0; i < ExprCopy.Count; i++)
{
if(ExprCopy[i].ToString().Equals("/"))
{
//get numeric value
double d1 = ExprCopy[i-1].dValue;
double d2 = ExprCopy[i+1].dValue;
//replace with value
ExprCopy[i-1] = new Token((d1/d2));
//remove operator and argument
ExprCopy.RemoveAt(i);
ExprCopy.RemoveAt(i);
i--;
i--;
}
}//end divisions loop
//multiplications loop
for (int i = 0; i < ExprCopy.Count; i++)
{
if(ExprCopy[i].ToString().Equals("*"))
{
//get numeric value
double d1 = ExprCopy[i-1].dValue;
double d2 = ExprCopy[i+1].dValue ;
//replace with value
ExprCopy[i-1] = new Token((d1*d2));
//remove operator and argument
ExprCopy.RemoveAt(i);
ExprCopy.RemoveAt(i);
i--;
i--;
}
}//end multiplications loop
//additions loop
for (int i = 0; i < ExprCopy.Count; i++)
{
if(ExprCopy[i].ToString().Equals("+"))
{
//get numeric value
double d1 = ExprCopy[i - 1].dValue;
double d2 = ExprCopy[i + 1].dValue;
//replace with value
ExprCopy[i - 1] = new Token((d1 + d2));
//remove operator and argument
ExprCopy.RemoveAt(i);
ExprCopy.RemoveAt(i);
i--;
i--;
}
}//end additions loop
//subtractions loop
for (int i = 0; i < ExprCopy.Count; i++)
{
if(ExprCopy[i].ToString().Equals("-"))
{
//get numeric value
double d1 = ExprCopy[i - 1].dValue;
double d2 = ExprCopy[i + 1].dValue;
//replace with value
ExprCopy[i - 1] = new Token((d1 - d2));
//remove operator and argument
ExprCopy.RemoveAt(i);
ExprCopy.RemoveAt(i);
i--;
i--;
}
}//end subtractions loop
if (ExprCopy.Count != 1)
{
//throw exception
}
return ExprCopy[0].dValue;
}
