45 lines
797 B
Java
45 lines
797 B
Java
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import java.lang.Math;
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/*
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* author: @AKS1996
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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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*/
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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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