do loop 4

[Forscher]

I am running SilverFox FTN 95 with Plato on a Windows PC with XP Prof.
I have run a program that contains an error, I have isolated the error as this:
&&&&&&&&&&&&&&&&&&&
do loop J=0,N
print*,'J=', J
end do
&&&&&&&&&&&&&&&&&&
This works fine for any value of N up to and including 297. However, for all values of N>297, say 1,000 I get J values printed running from (N-297) to N, i.e. 727,728,729,....1,000.
If it were an array, I could understand, but this loop doesn't require more memory the bigger it is. Or does it?
Has anyone any ideas?

 

[salgerman]

That's just weird...certainly the problem is not here, it is somewhere else...this is just a side effect...you may have arrays somewhere else that is stepping on somebody else's memory or something.

Have you compiled your program with run time error debugging flags, array length over-running or anything?

If the problem is really, really hard to solve, I have had to fall back to re-starting to "write" the program, meaning, I start a new file and start copying the code over in meaningful chunks, compile and run and see when the guilty piece of code transfers over...

 

[mikrom]

do [COLOR=red]loop[/color] J=0, N
...

would not work in fortran. It must be

do J=0, N
...

 

[salgerman]

Oh, I am not familiar with "SilverFox FTN 95 with Plato", I thought Forscher at least had the syntax correctly and truly had a memory problem, but if "do loop" is not allowed in SilverFox, like in the regular Fortran, then, that is true that the construct

do loop J=0, N
end do

is not quite correct for what is intended. Actually, it is equivalent to

do loopJ=0, N
end do

In other words, the space is being ignored and the loop variable should turn out to be "loopJ"...you can confirm this by writing that one instead. So, J is not being assigned anything for that matter.

 

[gummibaer]

Hi,
I do not know about the Silverfox compiler, but the docs of my good old Compaq Compiler give for the do statement the form

[name:] DO [label[, ] ] [loop-control]

with label to be a statement label while loop control is the well known index = start, end, step.
So if by chance Forscher's loop is an integer variable or constant and equals a label number, the results could be very unpredictable.

Norbert

 

[Forscher]

Sorry, my mistake. of course I wrote:
Do =1,N
Forscher

 

[salgerman]

Now, you went to the other extreme! "Do =1,N"? What happened to J? You know, there is such thing as copy/paste.

Lastly, of course you wrote ... so, are you saying that the word "loop" is not there? do you still have the problem first posted?

 

[Forscher]

Yes. sorry again. I am sitting watching TV and using my iPad.
I wrote:
Do J=1,1000
Print*, 'J=', J
End do
Apologies again
Forscher

 

[salgerman]

Oh, I am glad to hear we have your full attention.

 

[ArkM]

I have some good news for Fortran programmer(s): it's not (Silverfrost) Fortran issue.

By default Windows allocates console window buffer for 300 lines only. You can see last 300 lines of the program output (~297 printed lines + 3 lines of the Plato termination messages).

Change (increase) console window default buffer size (see Windows help - it's so easy...

 

[Forscher]

Thanks ArkM, you are a star. Before I read your message I had re-typed the program (it's really to small to be justify the name program) on a second, old machine I have downstairs and still got the same problem.
Thanks again
Forscher

 

[salgerman]

Ha! Good catch ArkM.

Forscher, in your last post, you used the word "still" ...does that mean that you still do not have a solution to your problem?

To test if ArkM is right, please run your program and re-direct your output from standard output (stdout) to a file, like this:

c:\myfolder\myprogram > outfile.txt

And see what you get.

 

[Forscher]

Hi Salgerman,
What I meant was that the behaviour of the program was the same in two PCs.
Here is my new code (cut & pasted).
%%%%%%%%%%%%%%%%%%%
program Jtest
implicit none
integer J
OPEN(unit=9,file='data.txt')
do J=1, 500
write(9,999) J
999 Format(I3)
end do
close(unit=9)
end program Jtest
%%%%%%%%%%%%%%%%%%%
This works fine. All values from 0 to 500 recorded in txt file.
Thanks for your comment. Thanks everyone for your interest.
Incidentally, it is many years since I last used FTN; last time, I had to put the program onto punched cards !!!
Good website this.
Cheers
Forscher