Re: Rethinking octave_idx_type

[John W. Eaton]

With this changeset

  http://hg.savannah.gnu.org/hgweb/octave/rev/21707d6a02c7

the --enable-64 configure option is now the default.  Here's the NEWS entry:

 ** On systems with 64-bit pointers, --enable-64 is now the default and
    Octave always uses 64-bit indexing.  However, if the configure
    script determines that the BLAS library uses 32-bit integers, then
    operations using the following libraries are limited to arrays with
    dimensions that are smaller than 2^31 elements:

      BLAS  LAPACK  QRUPDATE  SuiteSparse  ARPACK

    Additionally, the following libraries use "int" internally, so
    maximum problem sizes are always limited:

      glpk  Qhull

Yes, this change will break code that passes arrays of octave_idx_type 
integers to Fortran, and may cause issues with overflow if you pass 
octave_idx_type values to Fortran that are larger than 2^31-1.  Options 
are to fix the code or build Octave with --disable-64.

jwe