79 lines
2.5 KiB
Java
79 lines
2.5 KiB
Java
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/*
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This is a Java Program to Implement Regular Falsi Algorithm. Regular Falsi method is used for finding roots of functions.
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*/
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/**
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* Java Program to Implement Regular Falsi Algorithm
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**/
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public class RegularFalsi
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{
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/** function to find root for **/
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public double f(double x)
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{
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/** make your own function here but accordingly change (s, t) **/
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return Math.cos(x) - x * x * x;
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// return x * x * x - 3 * x + 4;
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// return Math.cos(x) - 3 * x + 1;
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// return 2 * x - Math.log(x)/Math.log(10) - 7;
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// return x * x - Math.log(x) - 12;
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}
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/** function to find root **/
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public double findRoot(double s, double t, double e, int m)
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{
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double r = 0.0,fr;
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int n, side = 0;
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/** starting values at endpoints of interval **/
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double fs = f(s);
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double ft = f(t);
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for (n = 0; n < m; n++)
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{
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r = (fs * t - ft * s) / (fs - ft);
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if (Math.abs(t - s) < e * Math.abs(t + s))
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break;
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fr = f(r);
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if (fr * ft > 0)
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{
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/** fr and ft have same sign, copy r to t **/
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t = r;
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ft = fr;
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if (side == -1)
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fs /= 2;
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side = -1;
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}
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else if (fs * fr > 0)
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{
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/** fr and fs have same sign, copy r to s **/
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s = r;
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fs = fr;
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if (side == +1)
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ft /= 2;
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side = +1;
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}
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else
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{
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/** fr * f_ very small (looks like zero) **/
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break;
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}
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}
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return r;
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}
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/** Main function **/
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public static void main(String[] args)
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{
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System.out.println("Regular Falsi Test ");
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RegularFalsi rf = new RegularFalsi();
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/** lower limit **/
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double s = 0;
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/** upper limit **/
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double t = 1;
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/** half of upper bound for relative error **/
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double e = 5E-15;
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/** number of iterations **/
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int iterations = 100;
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System.out.println("\nRoot : "+ rf.findRoot(s, t, e, iterations));
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}
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}
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/*
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Root : 0.8654740331016145
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