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
Subsequent invocations of
DTIME return values accumulated since the
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
DTIME is 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.|
|VALUES||The type shall be |
|TIME||The type shall be |
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