a question about fortran

[Charles Seman]

C Wang,

I would try the following (this hasn't been tested, so I don't know if
it will work...):

real a2d(ix,il)

IIREC=1
DO jj=1,JSTEPS/2
do k=1,kx
    READ (11, REC=IIREC) a2d
    WRITE (33, REC=IIREC) a2d
     IIREC=IIREC+1
end do
END DO

IREC=1   <-- new index for unit 44...
IIREC=JSTEPS/2+1
DO jj=JSTEPS/2+1,JSTEPS <-- note the "+1" added to "JSTEPS/2", so we
don't run out of data from unit 11...
do k=1,kx
    READ (11, REC=IIREC) a2d
     IIREC=IIREC+1
    WRITE (44, REC=IREC) a2d
     IREC=IREC+1
end do
END DO

The Fortran units are expecting records with "ix*il" words, and we're
doing unformatted reads / writes above, which we have used here in our
codes.  (depending on your computer system, you may not need the *4 in
the RECL specifier... if you've used the *4 in other codes with no
problems, then it is OK...)

I hope this helps,
Chuck

...

C wang wrote:

> Hi, can anybody help me with the question about how to read and write out
> files in fortran, I have a file which is bigger than 2G, so I cannot
> use it
> in grads directly, I need to divide it into 2 smaller files, the array of
> the original file is A(96,80,14) in 6000 days, if I want to write the
> file
> into 2 files, how can I do? this is what I have done, but it seems not
> right,
>
>        open (11,file='a11.dat',form='unformatted',
>     &       STATUS='OLD', ACCESS='direct', RECL=IX*IL*4)
>          OPEN (UNIT=33, FILE='33.dat', FORM='UNFORMATTED',
>     &        ACCESS='DIRECT', RECL=IX*IL*4)
>        OPEN (UNIT=44, FILE='44.dat', FORM='UNFORMATTED',
>     &        ACCESS='DIRECT', RECL=IX*IL*4)
>
>       IREC=1
>       DO jj=1,JSTEPS
>       DO k=1,kx
>       READ (11, REC=IREC) ((A(I,J,K),J=1,IL),I=1,IX)
>       IREC=IIREC+1
>       END DO
>       END DO
> c
>       IIREC=1
>       DO jj=1,JSTEPS/2
>       do k=1,kx
>       WRITE (33, REC=IIREC) ((A(I,J,K),J=1,IL),I=1,IX)
>       IIREC=IIREC+1
>       end do
>       END DO
>
>       IIREC=JSTEPS/2+1
>       DO jj=JSTEPS/2,JSTEPS
>       do k=1,kx
>       WRITE (44, REC=IIREC) ((ASAVE(I,J,K),J=1,IL),I=1,IX)
>       IIREC=IIREC+1
>       end do
>       END DO
>
> the error says: A direct access READ statement was executed past the
> end of
> file (unit=11, rec=84001).
>
> Thanks very much!
>
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--

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 Charles Seman                                Charles.Seman at noaa.gov
 U.S. Department of Commerce / NOAA / OAR
 Geophysical Fluid Dynamics Laboratory         voice: (609) 452-6547
 201 Forrestal Road                              fax: (609) 987-5063
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