function prova()
    f = @(x) x^2-9
    a = 0;   b = 10;
    k = 24; % <==== CAMBIARE QUESTO
    res = bisection(f, a, b, k);
    fprintf('Soluzione: %f\n', res);
end


function res = bisection(f, a_i, b_i, k)
  if f(a_i)*f(b_i) > 0
      fprintf('Segni sbagliati');
      res = (-1);
  end
  x_star = (a_i + b_i)/2.0;
  iteration_counter = 1;
  while iteration_counter < k
      if f(a_i)*f(x_star) > 0
        a_i = x_star;
      else
        b_i = x_star;
      end
      x_star = (a_i + b_i)/2;
      iteration_counter = iteration_counter + 1;
  end
  fprintf("Errore %f\n", x_star - 3);   % LA SO ANALITICAMENTE
  fprintf("Iterazioni max %f\n", iteration_counter);
  res = x_star;
end