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Re: Octave Limits
From: |
Przemek Klosowski |
Subject: |
Re: Octave Limits |
Date: |
Fri, 21 Nov 2003 11:49:42 -0500 (EST) |
I am attempting to write some test data to a file and have bumped into
the 2GB file size limit. Is there a really good reason why this limit
exists other than maybe no one has gotten around to updating the code?
I didn't check, but if you keep writing values to a file (as opposed
to creating a 2GB+ array in octave), you should be able to write files
limited only by the underlying file system---it is not an octave
issue; maybe no one has gotten around to updating the filesystem to
one that allows large files. Please say more about how you bumped
into the 2GB limit.
Secondly, when I write values to a file they seem to take up way too
much space and they can't be read properly. Below is an example script
that shows what I mean.
octave:1> datafile=fopen('./datafile.dat', 'w+', 'native');
octave:2> a = [0.1:0.1:1];
octave:3> fwrite(datafile, a, 'double', 'native');
octave:4> b=fread(datafile, length(a), 'double', 0, 'native');
octave:5> b
b = [](0x1)
octave:6> fclose(datafile);
octave:7> version
ans = 2.1.51
The file datafile.dat is 1180 bytes in length. I would have expected it
to be 8bytes * the length of 'a' = 80bytes. Also, fread didn't seem to
read back anything.
There are several issues here:
- fwrite needs a 'skip' argument: fwrite(datafile, a, 'double',0, 'native');
- when you fwrite, your file pointer is at the end of the file, so
fread will not read anything. If you fclose() and fopen(), it works.
fseek() should work, too.
- on my system (linux, octave 2.1.34) the file size is 80 bytes.
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-------------------------------------------------------------
- Octave Limits, Daryl Warkentin, 2003/11/21
- Octave Limits, John W. Eaton, 2003/11/21
- Re: Octave Limits,
Przemek Klosowski <=
- Re: Octave Limits, Daryl Warkentin, 2003/11/21
- Re: Octave Limits, Przemek Klosowski, 2003/11/21
- Re: Octave Limits, Daryl Warkentin, 2003/11/21
- Re: Octave Limits, John W. Eaton, 2003/11/21
- Re: Octave Limits, Dmitri A. Sergatskov, 2003/11/21
- Re: Octave Limits, Przemek Klosowski, 2003/11/24
- Re: Octave Limits, Daryl Warkentin, 2003/11/24
- Re: Octave Limits, Przemek Klosowski, 2003/11/21