public abstract class Series
    implements DoubleTerm, DoubleNext {

    public double sum(double a, double b) {
	double total = 0.0;
	while (!(a > b)) {
	    total += value(a);
	    a = result(a);
	}
	return total;
    }

    public static void main(String argv[]) {
	Series mySeries = new PiOver8Series();
	System.out.println(
	  "8.0 * mySeries.sum(1.0,1000.0) = "
	  + (8.0 * mySeries.sum(1.0, 1000.0)));
    }
}