SHHEIG Library Root Directory
-----------------------------

SHHEIG - Skew-Hamiltonian/Hamiltonian EIGensolvers - is a software 
library for the structure-preserving solution of generalized 
skew-Hamiltonian/Hamiltonian eigenvalue problems, including the 
computation of eigenvalues, eigenvalue reordering, and the stable 
deflating subspaces. There are versions for real and complex problems 
with variants for unfactored and factored problem formulations as well as
blocked codes for larger problems.
The main emphasis in SHHEIG is on numerical reliability of implemented
algorithms and the numerical robustness and efficiency of routines.
Providing algorithmic flexibility and the use of rigorous implementation
and documentation standards are other SHHEIG features.

The SHHEIG Library is available as standard Fortran 77 code in double
precision. Many user-callable subroutines are accompanied by an example 
program which illustrates the use of the subroutine and can act as a 
template for the user's own routines.

The SHHEIG Library root directory contains a few, basic files for the 
SHHEIG Library distribution and generation. When distributed, SHHEIG 
software comes with several filled-in subdirectories (doc, examples, mex,
src, test, and usersguide), and four files in this root directory:
- this file, readme,
- the main SHHEIG Library documentation index, libindex.html, and
- two template files for building the object library and executable 
  programs, make.inc and makefile.
The last two files might need few changes for being adapted to the 
specific platform used. Details about installing/updating the SHHEIG
software are given in the users' guide in the subdirectory usersguide.

After software installation, this directory will also contain the library 
file slicot.a for Unix platforms. The library file could then be linked 
in applications programs, as usual. Specific examples are contained in 
the directory examples. The on-line documentation of the SHHEIG user's 
callable routines is accessible via the main SHHEIG Library documentation 
index, libindex.html.

The SHHEIG Library is heavily built on SLICOT (Subroutine Library In 
COntrol Theory) and fufills its implementation and documentation 
standards. Furthermore, it is based on LAPACK (Linear Algebra PACKage) 
and BLAS (Basic Linear Algebra Subprograms). Therefore, these packages 
should be available on the platform used.

Basic References:

1. Benner, P., Byers, R., Losse, P., Mehrmann, V. and Xu, H.:
   Numerical Solution of Real Skew-Hamiltonian/Hamiltonian Eigenproblems.
   Tech. Rep., Technical University Chemnitz, Germany, Nov. 2007.

2. Benner, P., Byers, R., Mehrmann, V. and Xu, H.:
   Numerical Computation of Deflating Subspaces of Skew-Hamiltonian/
   Hamiltonian Pencils.
   SIAM J. Matrix Anal. Appl., 24(1):165-190, 2001.

3. Benner, P., Sima, V., Voigt, M.:
   FORTRAN 77 Subroutines for the Solution of Skew-Hamiltonian/
   Hamiltonian Eigenproblems - Part I: Algorithms and Applications.
   Max Planck Institute Magdeburg Preprint MPIMD/13-11, 2013.

4. Benner, P., Sima, V., Voigt, M.:
   FORTRAN 77 Subroutines for the Solution of Skew-Hamiltonian/
   Hamiltonian Eigenproblems - Part II: Implementation and Numerical 
   Results.
   Max Planck Institute Magdeburg Preprint MPIMD/13-12, 2013.