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