.. index:: Armadillo
.. _armadillo:

Armadillo
=========

Description
-----------

Armadillo is a C++ linear algebra library (matrix maths) aiming towards a good balance between speed and ease of use. Integer, floating point and complex numbers are supported, as well as a subset of trigonometric and statistics functions. Various matrix decompositions are provided through integration with LAPACK.

User instructions
-----------------

Armadillo is installed as a header-only library on the NFS server.  Updated versions are released quite regularly, and can be installed on request.  To use, for instance, Armadillo 7.960.1 first load the module:

.. code-block:: bash

    $ module load armadillo/7.960.1

Armadillo can then be used by including the Armadillo header in C++ source files, as shown in the example given in the Armadillo documentation:

.. code-block:: c++

    #include <iostream>
    #include <armadillo>

    using namespace std;
    using namespace arma;

    int main(int argc, char** argv)
    {
      mat A = randu<mat>(4,5);
      mat B = randu<mat>(4,5);
      
      cout << A*trans(B) << endl;
      
      return 0;
    }

The header files have been set to include the full functionality of Armadillo, and so a LAPACK and BLAS implementation must be included at link time.  This can be provided either by the standard :ref:`LAPACK` and BLAS libraries or (for better performance) by the installed :ref:`MKL` libraries.  The above example thus could be compiled with the gcc compilers using :ref:`LAPACK` or :ref:`MKL`  to provide the BLAS and LAPACK implementations:

.. code-block:: bash

    $ g++ example.cpp -llapack -lblas -lgfortran
    $ g++ example.cpp -Wl,--start-group -lmkl_gf_lp64 -lmkl_sequential -lmkl_core -Wl,--end-group -lpthread

and similarly for use with the Intel Compilers, namely:

.. code-block:: bash

    $ icpc example.cpp -llapack -lblas -lifcore
    $ icpc example.cpp -mkl

Documentation is available at http://arma.sourceforge.net/docs.html.

Source
------

http://arma.sourceforge.net

License
-------

GNU Lesser General Public License (LGPL) v3 (free in terms of speech and beer).

Admin notes
-----------

The compiled library is basically a container for a LAPACK and BLAS implementation so it is more flexible to leave Armadillo as a header library.  Installation amounts to downloading and extracting the tarball from http://arma.sourceforge.net and enuring ARMA_USE_LAPACK and ARMA_USE_BLAS macros are defined in include/armadillo_bits/config.hpp (default on newer versions).