BigPythagoras.java

import java.math.BigInteger;

public class BigPythagoras {

    /**
    *   Program:    BigPythagoras.java
    *   Purpose:    List of right-angled triangles whose sides are integers
    *   Creator:    Chris Clarke
    *   Created:    20.07.2014
    */

    public static void main(String[] args) {
        BigInteger a = new BigInteger("3");
        System.out.println("List of right-angled triangles whose sides are integers");
        System.out.println("a^2 + b^2 = c^2");
        System.out.println("===============");
        for (int i=0; i<12; i++) {
            a = calcSides(a);
        } // end while
    } // end main()

    public static BigInteger calcSides(BigInteger a) {
    // given a, calculate b and c and display all 3 values

        /*
            Pythagoras' Theorem states that:
            "In a right-angled triangle, the square on the hypotenuse is equal
            to the sum of the squares on the other two sides."

            a^2 + b^2 = c^2, where a, b and c are sides of a right-angled triangle,
            and c is the hypotenuse.
        */

        // b = ((a * a)-1)/2
        BigInteger b = (a.multiply( a).subtract( BigInteger.ONE)).divide(new BigInteger("2"));
        BigInteger c = b.add(BigInteger.ONE);

        // print sides of right-angled triangle
        System.out.println(a+", "+b+", "+c);

        return c; // will become argument for next function call
    } // end calcSides()
} // end class BigPythagoras