RAN function not working

nitin_amt · ‎10-03-2008

The code not working is below with line numbers at the start of each line. At line 6 when I call RAN(IFF), the value of IFF is still the same after line 6 is excuted. I would expect the value of IFF change after line 6. But this is not the case. Please help with the issue. Thanks in advance.

1. program

seven_11
2. USE IFPORT, ONLY: SRAND,RAN, RAND
3. integer*4 IFF
4. real*4 RAN2
5. DATA IFF /3333337/
6. RAN2=RAN(IFF)
7. IFF = 357
8. RAN2=RAN(IFF)
9. end program seven_11

Steven_L_Intel1 · ‎10-03-2008

Curious. I can reproduce this. I suggest using the standard intrinsic RANDOM_NUMBER instead, I'll report this to the developers.

Brian_Francis · ‎10-06-2008

I think it is working fine. The first call to RAN should use a large negative number as a seed for best results, but the important point to remember is that given the same seed value, the "random" results will be identical from one run to the next (handy for debugging). For a truly random result, try using an integer seed deived from the date and time.

Brian.

Brian_Francis · ‎10-06-2008

Replace "negative" with "odd" in my reply above. Next time I'll read the docs first and post second.

Steve_Nuchia · ‎10-08-2008

The doc give a specific example using 3. It doesn't work in 10.1.019.

Brian_Francis · ‎10-08-2008

Quoting - snuchia@statsoft.com

The doc give a specific example using 3. It doesn't work in 10.1.019.

I've tried the following with 10.1.021 and get results as advertised...

[cpp]program main
integer seed/3/
write (*,*) ran(seed)
write (*,*) ran(seed)
end[/cpp]

...which outputs...

[cpp]4.8220158E-05
0.3321905[/cpp]

Brian.

Kevin_D_Intel · ‎10-09-2008

I found that with IVF 10.x, the USE IFPORT interferes with RAN which the original sample program included.

If Brians program is modified slightly as shown:

[cpp]program main
use ifport
integer iseed /3/   
write (*,*) ran(iseed)
write (*,*) ran(iseed)
end[/cpp]

Then it prints:

6.7433808E-05

If line 2 is removed, then it prints:

4.8220158E-05

0.3321905

I reported this to the Fortran Front-end team and will follow-up when I know more. (Internal ref. CQ- 50312)

Steve_Nuchia · ‎10-09-2008

My bad: the using statement was something I put in there to get it compiling during the initial porting pass, long before we could actually run anything.

"It seemed like the thing to do at the time."

Kevin_D_Intel · ‎03-02-2009

This issue is fixed in the latest IVF 11.0 update, 11.0.072 (Windows).