public abstract class Integration
	{
	private double a; // the lower limit of the integration
	private double b; // the upper limit of the integration
	private int n; // the number of points for the integration

	public Integration()
		{
		setA(0);
		setB(1);
		setN(10);
		}

	public Integration(double a,double b,int n)
		{
		setA(a);
		setB(b);
		setN(n);
		}

	public double integrate()
		{
		int n = getN();
		if(!isEven(n) && this instanceof SimpsonsRule)
			setN(++n);
		double[] endpoints = getEndpoints();
		double h = calcH(endpoints[0],endpoints[1],n);
		double area = calcArea(n,h);
		return area;
		}

	protected double getA()
		{
		return a;
		}

	protected void setA(double a)
		{
		this.a = a;
		}

	protected double getB()
		{
		return b;
		}

	protected void setB(double b)
		{
		this.b = b;
		}

	protected int getN()
		{
		return n;
		}

	protected void setN(int n)
		{
		this.n = n;
		}

	protected double[] getEndpoints()
		{
		double[] endpoints =
			{
			getA(),
			getB(),
			};
		return endpoints;
		}

	protected double calcH(double a,double b,int n)
		{
		return (a + b) / (double)n;
		}

	protected abstract double calcArea(int n,double h);

	protected double calcXi(int i,double h)
		{
		return getA() + i * h;
		}

	protected double calcFunction(double x)
		{
		return Math.sin(x);
		}

	protected boolean isEven(int n)
		{
		return true;
		}
	}

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