Quick bissection implementation

bissection.cpp

//============================================================================
// Name        : bissection.cpp
// Author      : theantonioalmeida
// Description : Quick bissection implementation
//============================================================================

#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <cmath>
#include <limits>
using namespace std;

double f(double x);

int main() {

	double a, b, precision, lastPeriod;
	int counter = 0;

	cout << "a b precision "<< endl;
	cin >> a >> b >> precision;

	double m;

	while(abs(b-a) > precision) {
		m = (a+b)/2.0;

		if(signbit(f(a)) != signbit(f(m)))
			b = m;
		else
			a = m;

		//increment counter
		counter++;

		//infinite loop test
		if (lastPeriod == abs(b-a)) {
			cout << "The process entered an infinite loop." << endl;
			return -1;
		}
		else
			lastPeriod = abs(b-a);
	}

	cout << "The function's zero is " << setprecision(3) << fixed << (a+b)/2.0 << " with a precision of ";
	cout << (a-b)/2.0 << ", found after " << counter << " iterations." << endl;

	return 0;
}


double f(double x) {

	return pow(x,2)-2;
}