Time difference

[fanta2]

How can I determine how much time a programme needs for running?
like

starttime = day/hour/min
.
.
code
.
.stoptime= da/hour/min
timedifference = stoptime - starttime

can anyone help me the effective method to evaluate the time difference?

 

[gullipe]

Hello fanta2
Try this (the result is in seconds):

Program ttt

integer*4 ihr,imin,isec,i100th
real*8 time,time1,time2

call gettim(ihr,imin,isec,i100th)
time1 = 60.*(60.*ihr+imin) + isec + i100th/100.

c ......
c code
c ......

call gettim(ihr,imin,isec,i100th)
time2 = 60.*(60.*ihr+imin) + isec + i100th/100.

time = time2-time1

write(*,'(1x,f12.2)') time

end

Best wishes
GulliPe

 

[fanta2]

Ok thanks it works well but what will happen if the execution time is greater than 24 hours.

 

[gummibaer]

In the Salford documentation I found this example for an intrinsic function cpu_time:

real time1, time2
call cpu_time(time1)
...
...
! process
...
...
call cpu_time(time2)
print*,'processing time: ',time2-time1,' seconds'
end

Negative value of time denotes error condition. I could not check if there are any limits as to the time (I do not have such monsters running for days on end ;-)) .

Norbert

 

[fanta2]

Thanks - it works great. It gives me the time difference in seconds. I think I can convert the time to minutes or hours if necessary

 

[fanta2]

One more question - does the cpu_time function return the time elapsed from the start of the programme until the line of code for cpu_time?

 

[gummibaer]

I do not know - and the docs are unclear of this - what cpu time actually is. I did not check on this, just taking the differtence in seconds was okay for me - I never worked out, what cpu_time=0 might be. But taking time1 immediately after program start and time2 immediately before stop should come as close as could be to total elapsed time.

Norbert

 

[ArkM]

There is

SUBROUTINE SECONDS_SINCE_1980@(DR)
REAL(KIND=2) DR

in Salford FTN95 RTL.

...should be used when making timings which straddle midnigt.