47 lines
1017 B
Java
47 lines
1017 B
Java
package Others;
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import java.lang.Math;
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/**
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* Guass Legendre Algorithm
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* ref https://en.wikipedia.org/wiki/Gauss–Legendre_algorithm
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*
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* @author AKS1996
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*/
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public class GuassLegendre {
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public static void main(String[] args) {
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for (int i = 1; i <= 3; ++i)
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System.out.println(pi(i));
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}
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static double pi(int l) {
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/*
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* l: No of loops to run
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*/
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double a = 1, b = Math.pow(2, -0.5), t = 0.25, p = 1;
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for (int i = 0; i < l; ++i) {
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double temp[] = update(a, b, t, p);
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a = temp[0];
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b = temp[1];
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t = temp[2];
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p = temp[3];
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}
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return Math.pow(a + b, 2) / (4 * t);
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}
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static double[] update(double a, double b, double t, double p) {
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double values[] = new double[4];
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values[0] = (a + b) / 2;
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values[1] = Math.sqrt(a * b);
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values[2] = t - p * Math.pow(a - values[0], 2);
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values[3] = 2 * p;
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return values;
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}
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}
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