GaussLegendre.java

packagecom.thealgorithms.others;

/**
 * Guass Legendre Algorithm ref
 * https://en.wikipedia.org/wiki/Gauss–Legendre_algorithm
 *
 * @author AKS1996
 */
publicfinalclassGaussLegendre {
privateGaussLegendre() {
 }

publicstaticvoidmain(String[] args) {
for (inti = 1; i <= 3; ++i) {
System.out.println(pi(i));
 }
 }

staticdoublepi(intl) {
/*
 * l: No of loops to run
 */

doublea = 1;
doubleb = Math.pow(2, -0.5);
doublet = 0.25;
doublep = 1;
for (inti = 0; i < l; ++i) {
double[] temp = update(a, b, t, p);
a = temp[0];
b = temp[1];
t = temp[2];
p = temp[3];
 }

returnMath.pow(a + b, 2) / (4 * t);
 }

staticdouble[] update(doublea, doubleb, doublet, doublep) {
double[] values = newdouble[4];
values[0] = (a + b) / 2;
values[1] = Math.sqrt(a * b);
values[2] = t - p * Math.pow(a - values[0], 2);
values[3] = 2 * p;

returnvalues;
 }
}