DTIME — Execution time subroutine (or function)
DTIME(VALUES, TIME)initially returns the number of seconds of runtime since the start of the process’s execution in TIME. VALUES returns the user and system components of this time in
VALUES(2)respectively. TIME is equal to
VALUES(1) + VALUES(2).
Subsequent invocations of
DTIMEreturn values accumulated since the previous invocation.
On some systems, the underlying timings are represented using types with sufficiently small limits that overflows (wrap around) are possible, such as 32-bit types. Therefore, the values returned by this intrinsic might be, or become, negative, or numerically less than previous values, during a single run of the compiled program.
Please note, that this implementation is thread safe if used within OpenMP directives, i.e., its state will be consistent while called from multiple threads. However, if
DTIMEis called from multiple threads, the result is still the time since the last invocation. This may not give the intended results. If possible, use
This intrinsic is provided in both subroutine and function forms; however, only one form can be used in any given program unit.
VALUES and TIME are
INTENT(OUT)and provide the following:
User time in seconds.
System time in seconds.
Run time since start in seconds.
CALL DTIME(VALUES, TIME).
TIME = DTIME(VALUES), (not recommended).
VALUES The type shall be
TIME The type shall be
- Return value:
Elapsed time in seconds since the last invocation or since the start of program execution if not called before.
program test_dtime integer(8) :: i, j real, dimension(2) :: tarray real :: result call dtime(tarray, result) print *, result print *, tarray(1) print *, tarray(2) do i=1,100000000 ! Just a delay j = i * i - i end do call dtime(tarray, result) print *, result print *, tarray(1) print *, tarray(2) end program test_dtime
- See also: