Hi, I'm having trouble using the system_clock intrinsic with g95: it
is only returning count=0.  I get the same behavior on Linux x86 and
on Windows x86 under MinGW.  Here is my test program:

--------------------------------------------------------------
[sys_clock]$ g95 --version | head -n1
G95 (GCC 4.0.3 (g95 0.92!) May  5 2009)
[sys_clock]$ cat prog.f90
PROGRAM prog
  INTEGER :: clock, rate, cmax

  CALL SYSTEM_CLOCK(clock,count_rate=rate,count_max=cmax)
  PRINT*, 'size of int:', sizeof(clock)
  PRINT*, 'count:', clock
  PRINT*, 'rate:', rate
  PRINT*, 'max:', cmax
END PROGRAM prog
[sys_clock]$ g95 prog.f90
[sys_clock]$ a.out
 size of int: 4
 count: 0
 rate: 10000
 max: 2147483647
----------------------------------------------------------------------

Am I doing something wrong here?

Thanks,
John

Try the following.

PROGRAM prog
  INTEGER :: clock, rate, cmax, i, j
  REAL(8) :: D

DO i = 1, 5
  CALL SYSTEM_CLOCK(clock,count_rate=rate,count_max=cmax)
  PRINT*, 'size of int:', sizeof(clock)
  PRINT*, 'count:', clock
  PRINT*, 'rate:', rate
  PRINT*, 'max:', cmax
!!!!!!!!!!!!!!!!!!!
!! WORK A LITTLE !!
!!!!!!!!!!!!!!!!!!!
  DO j = 1, 999
     D = SIN(D) +0.25
  END DO
END DO
END PROGRAM prog

-Javier

Thanks, I tied that, and my output looks like:
[sys_clock]$ ./a.out
 count: 0
 count: 1
 count: 2
 count: 2
 count: 3

So it looks like it is counting.  However, I am trying to use this to
randomize the random number seed as described at
http://gcc.gnu.org/onlinedocs/gfortran/RANDOM_005fSEED.html, in which
case this will not work.  I am aware that with g95, calling random_seed
() without arguments will randomize the seed, but this does not work
on certain other compilers (e.g. gfortran, which just sets the seed to
a "default" value).

I guess my real question is whether or not there is a compiler-
independent mechanism for randomizing the seed?

John

Also from reading here:
http://www.ncsa.uiuc.edu/UserInfo/Resources/Hardware/IBMp690/IBM/usr/...,
it states that "The initial value of COUNT depends on the current
value of the processor clock in a range from 0 to COUNT_MAX."  It
seems like that by always starting the count at 0 when you make the
first call to system_clock, g95 is not producing the correct behavior.

You can search among system files to get a "number" that changes from
run to run.  Use INQUIRE, if the file is found, open it, read a
number, then return with this number.  For example, you can search for
the file

/proc/uptime

If it's there then it will contain different numbers at different
times.  With enough research you can write a subroutine that can look
for standard files on many types of OS's without ever having to call a
nonstandard subroutine such as system().

-Javier

How about using DATE_AND_TIME() to construct a seed? The output of the
function is bound to be different every time you run the program.

Evangelos

Thanks, this is also what Andy Vaught suggested, and we are now using
it.  See here: http://gcc.gnu.org/onlinedocs/gcc-4.0.2/gfortran/DATE_005fAND_005fTIM....
This function returns milliseconds, seconds, minutes, etc., and can
easily be used to generate a seed.  Works with both g95 and gfortran.

On Jun 15, 6:27 am, Evangelos Bertakis <eberta...@gmail.com> wrote: