Note: the following only applies to systems that have 64-bit pointers. Configuring Octave with --enable-64 cannot magically make a 32-bit system have a 64-bit address space.
On 64-bit systems, Octave uses 64-bit integers for indexing arrays by default. If the configure script determines that your 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:
Additionally, the following libraries use int internally, so
maximum problem sizes are always limited:
Except for GLPK and Qhull, these libraries may also be configured to use 64-bit integers, but most systems do not provide packages built this way. If you wish to experiment with large arrays, the following information may be helpful.
To determine the integer size of the BLAS library used by Octave, the following code can be executed:
clear all; N = 2^31; ## The following line requires about 8 GB of RAM! a = b = ones (N, 1, "single"); c = a' * b
If the BLAS library uses 32-bit integers, an error will be thrown:
error: integer dimension or index out of range for Fortran INTEGER type
Otherwise, if the BLAS library uses 64-bit integers, the result is:
c = 2^31 = 2147483648
Note that the test case above usually requires twice the memory, if
a and b are not assigned by a = b = ….
Note further, that the data type single has a precision of
about 23 binary bits. In this particular example no rounding errors
occur.
Generally, it is best to have all of these libraries in versions that support 32-bit indexing, or all of these libraries must support 64-bit indexing. Mixing libraries with 64-bit indexing with libraries with 32-bit indexing can cause unpredictable behavior including program crashes with possible loss of data.
The following instructions were tested with the development version of Octave and GCC 4.3.4 on an x86_64 Debian system and may be out of date now. Please report any problems or corrections on the Octave bug tracker.
The versions listed below are the versions used for testing. If newer versions of these packages are available, you should try to use them, although there may be some differences.
All libraries and header files will be installed in subdirectories of
$prefix64 (you must choose the location of this directory).
Reference versions for both libraries are included in the reference LAPACK 3.2.1 distribution from http://www.netlib.org/.
OPTS and NOOPT.
In the Makeconf file:
FFLAGS.
PREFIX to the top-level directory of your install tree.
make solib to make a shared library.
make install to install the library.
Pass the following options to make to enable 64-bit integers
for BLAS library calls. On 64-bit Windows systems, use
-DLONGBLAS="long long" instead.
CFLAGS='-DLONGBLAS=long' CXXFLAGS='-DLONGBLAS=long'
The SuiteSparse makefiles don’t generate shared libraries. On some systems, you can generate them by doing something as simple as
top=$(pwd)
for f in *.a; do
mkdir tmp
cd tmp
ar vx ../$f
gcc -shared -o ../${f%%.a}.so *.o
cd $top
rm -rf tmp
done
Other systems may require a different solution.
When configuring with cmake add the flag
-DSUNDIALS_INDEX_SIZE=64.
FFLAGS when running configure.
make to build the library.
make install to install the library.
Suggestions on how to compile ATLAS would be most welcome.
Both GLPK and Qhull use int internally so maximum problem
sizes may be limited.
Octave’s 64-bit index support is activated with the configure option --enable-64.
./configure \ LD_LIBRARY_PATH="$prefix64/lib" \ CPPFLAGS="-I$prefix64/include" LDFLAGS="-L$prefix64/lib" \ --enable-64
You must ensure that all Fortran sources except those in the
liboctave/external/ranlib directory are compiled such that INTEGERS are
8-bytes wide. If you are using gfortran, the configure script should
automatically set the Makefile variable F77_INTEGER_8_FLAG to
-fdefault-integer-8. If you are using another compiler, you
must set this variable yourself. You should NOT set this flag in
FFLAGS, otherwise the files in liboctave/external/ranlib will be
miscompiled.
Probably nothing special needs to be done for the following dependencies. If you discover that something does need to be done, please submit a bug report.