Fotran 计时函数， 注意区分CPU时间和系统时间 。
- Fortran 77 : etime()
call etime(tarray,t0)
! ... ...
call etime(tarray,t1)
print *, 'Elapsed time:', t1 - t0
- Fortran 90 : system_clock() 测量真实时间(real time).
integer ( kind = 4 ) clock_count
integer ( kind = 4 ) clock_count1
integer ( kind = 4 ) clock_count2
integer ( kind = 4 ) clock_max
integer ( kind = 4 ) clock_rate
! ... ...
call system_clock ( clock_count1, clock_rate, clock_max )
do i = 1, n
! ...some big calculation...
end do
call system_clock ( clock_count2, clock_rate, clock_max )
write ( *, * ) 'Elapsed real time = ', real ( t2 - t1 )
/ real ( clock_rate )
- Fortran 95 : cpu_time() 测量CPU时间(cpu time).
real (kind=8) t1
real (kind=8) t2
! ... ...
call cpu_time ( t1 )
do i = 1, n
! ...some big calculation...
end do
call cpu_time ( t2 )
write ( *, * ) 'Elapsed CPU time = ', t2 - t1
