function x=intfel2(a,b,e)
          n=ceil(log2((b-a)/e))
          fa=cos(a)-a-5;
          for i=1:n
                    x=(a+b)/2;
                    fx=cos(x)-x-5;
                    if fa*fx>0
                              a=x;
                              else b=x;
                    endif
          endfor
          x=(a+b)/2
end