import objectdraw.*;

/**
 * Representation for the variable X  regarded as an arithmetic expression
 * 
 * @author Russell C. Bjork 
 * @version March 20, 2008
 */
public class VariableX extends Node implements Expression
{
    /** Constructor
     */
    public VariableX() {
    }
    
    // Methods required by the Expression interface
    
    public String toString() {
        return "X";
    }
    
    public double evaluate(double x) {
        return x;
    }
    
    public Expression derivative() {
        return new Constant(1);
    }
    
    public Expression simplify() {
        return this;
    }
    
    public void draw(double x, double y, double width, DrawingCanvas canvas) {
        drawNode("X", x, y, width, canvas);
    }
}