Question

I need to plot a polynomial given a start point and an end point. I’ve looked at using the paincomponent to do do it, but I’m getting confused because the origin is in the top left corner and I need my grid lines to be dynamic.

How do I make it so I can create a dynamic scale and what java class is best used for plotting a function?

For example if the user were to enter -2 2 x^2 the plotter would need to create a grid that goes from -2 has 0 in the middle and 2 on the right for the x coordinates. However if the user enters x^3 we have negative coordinates in the y plane and I’ll need to slide the line containing the x coordinates up to accomidate.

Thanks!

Answer 1

The way I think you could do this(and I may be wrong) is to draw the y-line and x-line of your graph, and label the values for x and y using drawString at the correct position.
To illustrate this I did this example for you:

public void paintComponent(Graphics g)
{
    Graphics2D g2 = (Graphics2D) g;

    Point2D.Double from = new Point2D.Double(300, 100);
    Point2D.Double to = new Point2D.Double(300, 300);

    Line2D.Double line = new Line2D.Double(from, to);
    g2.draw(line);

    Point2D.Double from2 = new Point2D.Double(150, 200);
    Point2D.Double to2 = new Point2D.Double(450, 200);
    Line2D.Double line2 = new Line2D.Double(from2, to2);
    g2.draw(line2);

    g2.drawString("-1", 290, 215);
}

The drawString method would draw “-1” below 0. So you could use the same thing to draw -2 below -1, etc.

I know this sounds inefficient, but it’s the only way I can think of.

Hope someone else will have a better solution for you.