Regula-Falsi.cpp

/* Bisection Method */
#include <iostream>
#include <iomanip>
#include <math.h>
using namespace std;
float f(float x)
{
    return (x*x*x - 4*x - 9);
}
void bisect(float *x,float a,float b,int *itr){
    *x = (a + b)/2;
    ++(*itr);
    cout << "Iteration no." <<setw(3) << *itr
        << "X = " << setw(7) << setprecision(5)
        << *x << endl;
}
int main(){
    int itr = 0, maxitr;
    float x, a, b, aerr, x1;
    cout << "Enter the values of a,b,"
    << "allowed error, maximum iterations" << endl;
    cin >> a >> b >> aerr >> maxitr;
    cout << fixed;
    bisect(&x,a,b,&itr);
    do{
        if (f(a)*f(x) < 0)
        b = x;
        else
        a = x;
        bisect (&x1,a,b,&itr);
        if (fabs(x1-x) < aerr){
            cout << "After" << itr << "iterations, root"
            << "=" << setw(6) << setprecision(4)
            << x1 << endl;
        return 0;
        }
        x = x1;
    } while (itr < maxitr);
    cout << "Solution does not converge,"
    << "iterations not sufficient" << endl;
    return 1;
}