public static string Table(RPN rpn, RPN.Node expression, RPN.Node variable, RPN.Node a, RPN.Node b, RPN.Node frequencey)
{
//A regular function
PostFix math = new PostFix(rpn);
double start = math.Compute(a.ToPostFix().ToArray());
double end = math.Compute(b.ToPostFix().ToArray());
double freq = math.Compute(frequencey.ToPostFix().ToArray());
double PrevAnswer = 0;
math.SetPolish(expression.ToPostFix().ToArray());
double DeltaX = end - start;
double n = DeltaX / freq;
int max = (int)Math.Ceiling(n);
Tables <double> table = new Tables <double>(new Config()
{
Format = rpn.Data.DefaultFormat,
Title = "Table"
});
table.Add(new Schema(variable.Token.Value));
table.Add(new Schema($"f({variable.Token.Value})"));
for (int x = 0; x <= max; x++)
{
double RealX = start + x * DeltaX / n;
math.SetVariable("ans", PrevAnswer);
math.SetVariable(variable.Token.Value, RealX);
double answer = math.Compute();
table.Add(new double[] { RealX, answer });
PrevAnswer = answer;
math.Reset();
}
return(table.ToString());
}
public static double Approximate(RPN rpn, RPN.Node expression, RPN.Node variable, RPN.Node a, RPN.Node b, RPN.Node frequencey, List <ApproximationModes> modes)
{
PostFix math = new PostFix(rpn);
RPN.Token[] Polish = expression.ToPostFix().ToArray();
double start = math.Compute(a.ToPostFix().ToArray());
double end = math.Compute(b.ToPostFix().ToArray());
bool multiplyByNegativeOne = end < start;
if (multiplyByNegativeOne)
{
double temp = start;
start = end;
end = temp;
}
double freq = math.Compute(frequencey.ToPostFix().ToArray());
math.SetPolish(Polish);
double Rsum = 0;
double Lsum = 0;
double MidSum = 0;
double PrevAnswer = 0;
double f_a = 0;
int count = 0;
double DeltaX = end - start;
double n = DeltaX / freq;
int max = (int)Math.Ceiling(n);
for (int x = 0; x <= max; x++)
{
double RealX = start + x * DeltaX / n;
math.SetVariable("ans", PrevAnswer);
math.SetVariable(variable.Token.Value, RealX);
double answer = math.Compute();
if (x == 0)
{
f_a = answer;
}
if (x % 2 == 0)
{
if (x < max)
{
Rsum += answer;
}
if (x > 0)
{
Lsum += answer;
}
}
else
{
MidSum += answer;
}
PrevAnswer = answer;
math.Reset();
count++;
}
double LApprox = (2 * Rsum * DeltaX / n);
double RApprox = (2 * Lsum * DeltaX / n);
double MApprox = (2 * MidSum * DeltaX / n);
double TApprox = (LApprox + RApprox) / 2;
freq = freq * 2;
n = DeltaX / freq;
double Simpson = double.NaN;
if (n % 2 == 0)
{
Simpson = (TApprox + 2 * MApprox) / 3;
}
Dictionary <ApproximationModes, double> approximations = new Dictionary <ApproximationModes, double>()
{
{ ApproximationModes.Simpson, Simpson },
{ ApproximationModes.Midpoint, MApprox },
{ ApproximationModes.Trapezoidal, TApprox },
{ ApproximationModes.Left, LApprox },
{ ApproximationModes.Right, RApprox }
};
//Return based on mode requested
for (int i = 0; i < modes.Count; i++)
{
double approximation = approximations[modes[i]];
if (!double.IsNaN(approximation))
{
return(multiplyByNegativeOne ? approximation * -1 : approximation);
}
}
return(multiplyByNegativeOne ? approximations[modes[0]] * -1 : approximations[modes[0]]);
}
