Read and process a Fortran90 binary file

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Carola Forlini
Carola Forlini about 10 hours 前
评论： Carola Forlini about 8 hours 前
Hi,
I have a Fortran90 code where a variable called 'stream' is defined such that it stores certain variable every nstep:
open(19,file='stream',form='UNFORMATTED',position='append')
if(mod(NSTEP,100).eq.0)then
write(19)NSTEP,U,W,zeta
endif
How can I properly read the file in Matlab for postprocessing?
FYI, the fortran code is built with double precision.
Thank you
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Walter Roberson
Walter Roberson about 8 hours 前
The FORTRAN runtime system embeds the record boundaries in the data by inserting an INTEGER*4 byte count at the beginning and end of each unformatted sequential record during an unformatted sequential WRITE. The trailing byte count enables BACKSPACE to operate on records.
https://docs.oracle.com/cd/E19957-01/805-4939/6j4m0vnc4/index.html
Carola Forlini
Carola Forlini about 8 hours 前
I am attaching an extract of the file.
NSTEP is an integer = 2000
U, W, zeta are matrices = 32x512
Thank you

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回答（1 个）

Les Beckham
Les Beckham about 9 hours 前
编辑：Les Beckham about 9 hours 前
It would help to have a sample file to experiment with.
Nevertheless, assuming that the write call that you have shown is the only thing that writes to this file in your Fortran code, I would suggest something like this using fread and reshape:
fid = fopen('your_file_name.ext', 'rb');
A = fread(fid);
data = reshape(A, 4, numel(A)/4)';
nstep = A(:,1);
U = A(:,2);
W = A(:,3);
zeta = A(:,4);
Note that you might run into endian-ness issues if your Fortran code runs on a different architecture than your Matlab is running on. See the documentation for the machinefmt option to fread if necessary.
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Walter Roberson
Walter Roberson about 8 hours 前
form='UNFORMATTED' has record length markers before and after each record.
Walter Roberson
Walter Roberson about 8 hours 前
If you start with fread(fid, 1, 'integer*4') and discard that, and thereafter fread() with a skip field of 8 then it should be properly positioned to fread() more.
Unfortunately we are not told the size of NSTEP, U, W, zeta

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