integer, parameter :: i8 = selected_int_kind(15) integer (kind=i8) :: count, count_rate, count_2 x = 1.2 call system_clock (count, count_rate) call f call system_clock (count_2) if (count_rate == 10**9) then print *,"The call to f used ", (count_2-count), "Nanoseconds" else print *,"The call to f used ", (count_2-count)/real(count_rate)*1e9, "Nanoseconds" end if