function x=intfel(a,b,e)
  n=ceil(log((b-a)/e)/log(2))
  fa=sin(a)+2-exp(a)
  for i=1:n-1
    x=(a+b)/2
    fx=sin(x)+2-exp(x)
    if fa*fx<0
      b=x
      else a=x
    endif
  endfor
  x=(a+b)/2