Re: Max file Size for fwrite() function

[Jaroslav Hajek]

On Tue, May 26, 2009 at 1:37 PM, David Kremer <address@hidden> wrote:
> Hello everyone,
>
> it seems that octave has a max file size available with the fwrite() i/o
> function.
>
> Tonight, I ran a script which write on the disk data matrix with "float"
> precision.
>
> The total amount of data should be respectively 2.5 Go and 3.5 Go, but
> my two files are given with a size of 2 Go.
>
> So, I lost a big quantity of data. I almost sure I have enough drive
> space, so I guess it's a built-in limitation of the fwrite function.
>
> Since I'm not an expert in system programming, I don't know really well
> why my file size is limited up to 2 Go.
>
> That could a problem about int max size on 32 bits processor, or
> something like that.
>
> I'm running Debian lenny 5.0.1, and the octave version is 3.0.1 [1].
>
> My CPU is Genuine Intel(R) CPU           T2080  @ 1.73GHz.
>
> If you know any mean to get over this limitation, please let me know how
> to do this.
>
> Thank you very much for your support.
>
> [1] http://packages.debian.org/stable/math/octave3.0
>

Hi,

can you reproduce the problem in the form of a script that fails? Note
that Octave is usually compiled with 32-bit indexing (LAPACK and BLAS
being the main reason). That's why it can't handle arrays bigger than
~ 2*10^9 elements. However, with my 3.2.0 RC3 build, I have no problem
creating a >2GB file by repeatedly writing large arrays to it, so I
can't confirm the problem.

cheers


-- 
RNDr. Jaroslav Hajek
computing expert & GNU Octave developer
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz