This applet has two functions: First, it can be used to plot user supplied data. It can also be used to test if a user supplied quadratic function (a function of the form y = a x^2 + b x + c) fits the given data by plotting the function. Use it as follows:

  1. The sequence of operations must be as follows:
    1. The user must enter the data to plot in the DATA area. Though the variables default to x (the independent variable) and y (the dependent variable), they can be renamed. Renaming them will cause the graph to be updated. The values are entered one per line. Error messages will be displayed in the MESSAGES area if the data does not have the correct format, that is if the data is not a number.
    2. The user can then plot the data by pressing the "PLOT DATA" button.
    3. The user supplies the coefficients defining the function to test.
    4. The user plots the function by pressing the "TRY" button.
  2. The buttons work as follows:
    1. CLEAR will clear the DATA area, the PLOT area and the MESSAGES area.
    2. PLOT DATA will plot the data as points.
    3. TRY will plot the quadratic function corresponding to the coefficients supplied by the user.
  3. The PLOT area (top, right) will show the plot.
  4. The MESSAGES area is used to communicate with the user. Errors will be displayed there, for example if the number of values is not the same for both variables. Information will also be displayed there.