Re: Octave 3.0.1 Scientific Linux 5.1 (RHAT) build failure

[John W. Eaton]

On  9-May-2008, Francesco Potorti` wrote:

| >If no one runs on a 64-bit platform none of the bugs of 64-bit systems
| >will be found.
| 
| I am running a dual core amd64 with Debian testing, and I see no
| problems with Octave.  Isn't that built with 64 bits?

Unless you built it with the --enable-64 configure option, then no,
not really.  With --enable-64, array sizes and indices are represented
as 64-bit integers.  Without it, they are still just 32-bit integers.

The hard part about making Octave work properly as a 64-bit
application is interfacing with other libraries and Fortran code.
Also, if you need the larger array size limits allowed by the 64-bit
version, you will likely need large file support, and so far no one
has done the work for that.

BTW, the limit is 2^31 (2GB, or approximately 268x10^6 double
precision elements, which is approximately a 16,000x16,000 matrix) not
2^32 (4GB) because we have to used signed integers for array sizes and
indices because of our dependence on Fortran code like the BLAS and
LAPACK.  However, on your 64-bit system with a "32-bit" Octave, the
limit of any individual array is 2GB, but you can have more than one.
So unless you really need to work with individual arrays that are
larger than 2GB, you probably don't need to compile Octave with
--enable-64.

jwe