#include <stdio.h>
 
double f (double x);
int sameSign(double x, double y);
double middleOf(double x, double y);
int isSmallNumber(double x);

/* Udrykning - ikke indrykning */
double findRootBetween(double a, double b)
{
    double l = a, u = b;
    while (!isSmallNumber(f(middleOf(l, u)))) { 
  if(sameSign(f(middleOf(l, u)), f(u)))
      u = middleOf(l, u);
  else 
      l = middleOf(l, u);
  }
        return middleOf(l, u);
}  

int main (void)
{
    findRootBetween(-3.0, 5.0);
}