# Eigenvalue SoLvers for Petaflop-Applications (ELPA)

## Current Release

The current release is ELPA 2017.05.002. The current supported API version is 20170403. This release supports the earliest API version 20170403.

##
*ELPA*

About The computation of selected or all eigenvalues and eigenvectors of a symmetric (Hermitian) matrix has high relevance for various scientific disciplines. For the calculation of a significant part of the eigensystem typically direct eigensolvers are used. For large problems, the eigensystem calculations with existing solvers can become the computational bottleneck.

As a consequence, the *ELPA* project was initiated with the aim to develop and
implement an efficient eigenvalue solver for petaflop applications, supported
by the German Federal Government, through BMBF Grant 01IH08007, from
Dec 2008 to Nov 2011.

The challenging task has been addressed through a multi-disciplinary consortium of partners with complementary skills in different areas.

The *ELPA* library was originally created by the *ELPA* consortium,
consisting of the following organizations:

- Max Planck Computing and Data Facility (MPCDF), fomerly known as Rechenzentrum Garching der Max-Planck-Gesellschaft (RZG),
- Bergische Universität Wuppertal, Lehrstuhl für angewandte Informatik,
- Technische Universität München, Lehrstuhl für Informatik mit Schwerpunkt Wissenschaftliches Rechnen ,
- Fritz-Haber-Institut, Berlin, Abt. Theorie,
- Max-Plack-Institut für Mathematik in den Naturwissenschaften, Leipzig, Abt. Komplexe Strukutren in Biologie und Kognition, and
- IBM Deutschland GmbH

*ELPA* is distributed under the terms of version 3 of the license of the
GNU Lesser General Public License as published by the Free Software Foundation.

##
*ELPA*

Obtaining There exist several ways to obtain the *ELPA* library either as sources or pre-compiled packages:

- official release tar-gz sources from the
*ELPA*webpage - from the
*ELPA*git repository - as packaged software for several Linux distribtutions (e.g. Debian, Fedora, OpenSuse)

## Terms of usage

Your are free to obtain and use the *ELPA* library, as long as you respect the terms
of version 3 of the license of the GNU Lesser General Public License.

No other conditions have to be met.

Nonetheless, we are grateful if you cite the following publications:

T. Auckenthaler, V. Blum, H.-J. Bungartz, T. Huckle, R. Johanni, L. Kr\"amer, B. Lang, H. Lederer, and P. R. Willems, "Parallel solution of partial symmetric eigenvalue problems from electronic structure calculations", Parallel Computing 37, 783-794 (2011). doi:10.1016/j.parco.2011.05.002.

Marek, A.; Blum, V.; Johanni, R.; Havu, V.; Lang, B.; Auckenthaler, T.; Heinecke, A.; Bungartz, H.-J.; Lederer, H. "The ELPA library: scalable parallel eigenvalue solutions for electronic structure theory and computational science", Journal of Physics Condensed Matter, 26 (2014) doi:10.1088/0953-8984/26/21/213201

##
*ELPA* library

Installation of the *ELPA* is shipped with a standard autotools automake installation infrastruture.
Some other libraries are needed to install *ELPA* (the details depend on how you
configure *ELPA*):

- Basic Linear Algebra Subroutines (BLAS)
- Lapack routines
- Basic Linear Algebra Communication Subroutines (BLACS)
- Scalapack routines
- a working MPI library

Please refer to the **INSTALL document** on details of the installation process and
the possible configure options.

##
*ELPA*

Using Please have a look at the "**USERS_GUIDE**" file, to get a documentation or at the online doygen
documentation, where you find the definition of the interfaces.

##
*ELPA*

Contributing to It has been, and is, a tremendous effort to develop and maintain the
*ELPA* library. A lot of things can still be done, but our man-power is limited.

Thus every effort and help to improve the *ELPA* library is higly appreciated.
For details please see the CONTRIBUTING document.