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Re: Octave Limits

From: Daryl Warkentin
Subject: Re: Octave Limits
Date: Fri, 21 Nov 2003 10:37:01 -0600

On Fri, 2003-11-21 at 10:31, John W. Eaton wrote:
> On 21-Nov-2003, Daryl Warkentin <address@hidden> wrote:
> | First of all I am new to this list and just want to say thank you to all
> | of the people who put so much hard work into octave. It's great.
> | 
> | Now the questions.
> | 
> | 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?
> | If it is the code thing maybe I can help.
> What kind of system are you using?  Does it support files larger than
> 2GB?
> In the last day there has been some discussion about this on the
> octave-maintainers mailing list, at least having to do with the type
> of the value returned by ftell and used by fseek (which need to be
> bigger than a 32-bit int to support large files).  But this may not be
> enough to properly support large files.  If you'd like to contribute
> to the discussion, then please subscribe to the octave-maintainers
> list.
> | 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:3> help fwrite
>   fwrite is a built-in function
>    - Built-in Function: COUNT = fwrite (FID, DATA, PRECISION, SKIP, ARCH)
> If you want to specify ARCH, you also must specify SKIP.  But since
> the default is 'native', then I don't think it is necessary here (or
> in the fopen call).  Perhaps Octave should issue an error message
> here, since you supplied SKIP as a string.  It used to do that, so I
> will see about fixing it.
> | octave:4> b=fread(datafile, length(a), 'double', 0, 'native');
> | octave:5> b
> | b = [](0x1)
> You didn't rewind the file, so there was nothing to read.

Another case of not reading the documentation properly. Thanks for the

Daryl Warkentin, P. Eng.
Hardware Engineering
SED Systems

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