Re: sizemax() and 64-bit systems

[Mike Miller]

On Mon, 13 Aug 2012, Martin Helm wrote:

> Just a very short comment from my side, since I do not use the
> enable-64bit switch when compiling octave. The problem is obviously not
> so much if the libraries are compiled for 64bit (all my libraries are),
> but that the default size for an integer in the fortran libraries is set
> to 8 byte instead of 4 byte, at least that was my understanding last
> time I looked at it.
> I can be completely wrong here.


I was getting some info from here...

http://www.gnu.org/software/octave/doc/interpreter/Compiling-Octave-with-64_002dbit-Indexing.html

...which included this:

"all numerical libraries used by Octave will also need to use 64-bit 
integers for array dimensions and indexing. In most cases, this means they 
will need to be compiled from source since most (all?) distributions which 
package these libraries compile them with the default Fortran integer 
size, which is normally 32-bits wide."

So the problem is with the indexing, not with the memory addressing.

I guess FORTRAN uses signed integers for indexing which really means we 
have 31 bytes for positive indexing, not 32.  I don't understand the 
negative index, but I'm not much of a computer scientist!

Mike