Example of using the Bisection method, page 86 of "Competitive programming 3" by Steven & Felix Halim

bisection.cpp

#include <iostream>
#include <iomanip>
#include <algorithm>
using namespace std;
const double EPS = 1e-10;
double f(double d, int m, int v, double i)
{
    double loanLeft = v;
    for(int j = 0; j < m; ++j)
    {
        loanLeft = loanLeft*(1 + i/100);
        loanLeft -= d;
    }
    return loanLeft;
}
double bisection(int m, int v, double i)
{
    double start = 0.01;
    double end = 1100;
    double mid;
    while(fabs(start - end) > EPS)
    {
        mid = (start + end) / 2;
        cout<<"Current mid: "<<mid<<", and current f: "<<f(mid, m, v, i)<<endl;
        if(f(mid, m, v,i) < 0) end = mid;
        else start = mid;
    }
    cout<<fixed<<setprecision(2)<<"D is: "<<mid<<endl;
}
int main()
{
    int m = 2, v = 1000, i = 10;
    bisection(m, v, i);
    return 0;
}