// Second constructor takes a string equation, string variable and a color
// This constructor is called by the other constructor to assign properties and instantiates the Evaluator object
public Function(string equation, string variable, Color colour)
{
Equation = equation;
Variable = variable;
Colour = colour;
evaluator = new Evaluator();
}
// Method is called when the user hits a key when in the target point textbox on the differentiation tab
// If the user presses the enter key, update the TargetPoint control in the DifferentiationPlotter object instance
private void TargetPointTextBoxKeyDown(object sender, KeyEventArgs e)
{
// If the enter key has been pressed
if (e.KeyCode == Keys.Enter)
{
try
{
// Create an Evaluator object to evaluate the text in the target point textbox
// This allows the user to enter input such as 'pi' into the textbox
var eval = new Evaluator();
// Evaluate the expression and get a result
var result = (float) eval.Evaluate(TargetPointTextBox.Text);
if((result >= -9999F) && (result <= 9999F))
{
// If the result is valid, assign the TargetPoint of the grapher to the result
differentiationPlotter.TargetPoint = (float) result;
}
else
{
// Prompt the user if the value is not valid
MessageBox.Show("Target Point must be between -9999 and 9999", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
catch (Exception)
{
// Prompt the user if the text entered could not be evaluated into a numerical result
MessageBox.Show("Invalid Target Point", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
}
// Method calculates an iterational equation up to a certain number
// At first a user specified number is inserted into the equation and a result is calculated
// For every subsequent iteration, the most recent calculated value is inserted to give a new result
// Method populates the listview control with the results
private void CalculateResults()
{
// Create a new Function object with the equation entered in the equation textbox to allow the equation
// to be evaulated
var function = new Function(EquationTextBox.Text);
var eval = new Evaluator();
// Clear the listview component to remove previous results
ResultsListView.Items.Clear();
// A variable to hold the current calculated value
double result;
// The number of iterations to use
int numIterations = (int) NumIterationsUpDown.Value - 1;
// If the number entered in the first iteration textbox is numerical
try
{
// Evaluate the first iteration
result = eval.Evaluate(FirstIterationTextBox.Text);
}
catch(Exception)
{
// Prompt the user if there was an error evaluating
MessageBox.Show("Invalid first iteration", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
//Add the first item to the listview. The first iteration is just the first value entered by the user
var item1 = new ListViewItem("1");
item1.SubItems.Add(result.ToString(CultureInfo.InvariantCulture));
// Add the first result to the listview
ResultsListView.Items.Add(item1);
try
{
// Loop through each iteration
for (int i = 0; i < numIterations; i++)
{
// Calculate the new result by evaluating the function at the current result
double newRes = Math.Round(function.Evaluate(result.ToString(CultureInfo.InvariantCulture)), 5);
// Add the new result to the listview control
var item = new ListViewItem((i + 2).ToString(CultureInfo.InvariantCulture));
item.SubItems.Add(newRes.ToString(CultureInfo.InvariantCulture));
ResultsListView.Items.Add(item);
// Set the current result to the newly calculated result to get ready for the next iteration
result = newRes;
}
}
catch (Exception)
{
// Prompt user if there were errors evaluating the function
MessageBox.Show("Invalid Equation", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
// Method is called when the user presses a key in any of the integration parameter textboxes
// If the enter key has been pressed, update the properties in the AreaPlotter instance with the new parameters
private void AreaParamsChange(object sender, KeyEventArgs e)
{
// If the enter key ahs been pressed
if (e.KeyCode == Keys.Return)
{
try
{
// Create an Evaluator object to evaluate the text in each parameter textbox
// This allows the user to enter input such as 'pi' into a textbox
var eval = new Evaluator();
// Update the properties in the AreaPlotter with the evaluated results
areaPlotter.Lower = (float) eval.Evaluate(LowerLimitTextBox.Text);
areaPlotter.Upper = (float) eval.Evaluate(UpperLimitTextBox.Text);
var t = (int) eval.Evaluate(IterationsTextBox.Text);
// Bounds check the number of iterations to prevent performance issues
if (t > 99)
throw new Exception("Iterations must be less than 99");
if(t <= 0)
throw new Exception("Number of iterations must be greater than zero");
// If the current graph is a SimpsonPlotter, then the number of iterations cannot be odd
if (t % 2 != 0 && areaPlotter is SimpsonPlotter)
throw new Exception("Must have even number of strips");
areaPlotter.Iterations = (int) eval.Evaluate(IterationsTextBox.Text);
e.Handled = true;
}
catch (Exception exc)
{
// Prompt the user if any parameter inserted could not be evaluated into a numerical result
MessageBox.Show(exc.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
}