Bug#743642: Suggestion: Enable 64-bit Index Support on AMD64

[Kumar Appaiah]

Hi.

On Fri, Apr 04, 2014 at 03:46:48PM +0100, Barak A. Pearlmutter wrote:
> Package: libarmadillo-dev
> Version: 1:4.100.2+dfsg-2
> Severity: wishlist
> 
> When compiling the mlpack machine learning library, which links to
> Armadillo, the configuration scripts spits out this bon mot:
> 
>   -- Found Armadillo: /usr/lib/libarmadillo.so (found suitable version "4.100.2", required is "3.6.0") 
>   CMake Warning at CMakeLists.txt:81 (message):
>     This is a 64-bit system, but Armadillo was compiled without 64-bit index
>     support.  Consider recompiling Armadillo with ARMA_64BIT_WORD to enable
>     64-bit indices (large matrix support).  MLPACK will still work without
>     ARMA_64BIT_WORD defined, but will not scale to matrices with more than 4
>     billion elements.
> 
> which sounds reasonable.
> 
> At least, it sounds reasonable when you're doing machine learning with
> big datasets.  (I suppose there are other circumstances where 32-bit
> indexes make more sense.  But that argument would likely apply to all
> pointers.  Which would constitute a new 32-bit-user-pointers
> amd64-instructions "architecture".  Which is in fact under active
> development.  But it does seem hard to pretty hard to argue against
> 64-bit index support on arch amd64.)

Sorry for the late response. I will try to see the best way to handle
this. However, this could be handled at the mlpack level by just
adding a #define appropriately before the armadillo include, for the
time being.

I will find out the best way to handle this and add it.

Kumar
-- 
Kumar Appaiah