Coursera - Computer Science: Programming With A Purpose

Write a program GeneralizedHarmonic.java that takes two integer command-line arguments n and r and uses a for loop to compute the n^th generalized harmonic number of order r, which is defined by the following formula:

    H(n, r) = 1 / 1^r + 1 / 2^r + ⋯ + 1 / n^r.

For example, H(3, 2) = 1 / 1² + 1 / 2² + 1 / 3² = 4936 ≈ 1.361111.

~/Desktop/loops> java GeneralizedHarmonic 1 1
1.0

~/Desktop/loops> java GeneralizedHarmonic 2 1
1.5

~/Desktop/loops> java GeneralizedHarmonic 3 1
1.8333333333333333

~/Desktop/loops> java GeneralizedHarmonic 1 2
1.0

~/Desktop/loops> java GeneralizedHarmonic 2 2
1.25

~/Desktop/loops> java GeneralizedHarmonic 3 2
1.3611111111111112

Note: you may assume that n is a positive integer.

The generalized harmonic numbers are closely related to the Riemann zeta function, which plays a central role in number theory.

Note: the above description is copied from Coursera and converted to markdown for convenience

Solution:

public class GeneralizedHarmonic {

    public static void main(String[] args) {
        final int n = Integer.parseInt(args[0]);
        final int r = Integer.parseInt(args[1]);

        double sum = 0.0;
        for (int i = 1; i <= n; i++) {
            sum = sum + (1 / Math.pow(i, r));
        }
        System.out.println(sum);
    }
}

Link To: Java Source Code