Question

Not too sure where I am going wrong. I need to sum the first 16 elements of the series: 1, 3, 9, 27, 81…. using the method total The code does so by creating an instance of Geometric1 that will be of typ Seq.

The total method prints a value 7174454.0 but i should be getting 21523360.

public class Geometric1 implements Seq{

private double b;
public static double result = 0.0;

public Geometric1(double b) {
    this.b = b;
}


public double valAtIndex(int i) {
    // TODO Auto-generated method stub
    return Math.pow(b, i);
}

public static double total() {

    Seq s = new Geometric(3.0);

    for (int i = 0; i < 15; i++) {
        result += s.valAtIndex(i);
    }

    return result;
}

public static void main(String[] args) {

    System.out.println(total());}
}

Answer 1

You’re close. You just need to adjust your loop to run 16 times.

Keep result initialized to 0 (you’ve edited the post multiple times), and change your loop as follows:

for (int i = 0; i <= 15; i++) {
    result += s.valAtIndex(i);
}