a code for computing the periodic real Schur decomposition

psSchur is an experimental FORTRAN77 double precision code to compute the periodic
Schur decomposition. The package also contains interfaces to Matlab for most
subroutines. The latter are written in C. The package has been developed on
a PC using Matlab 5.3 and the Microsoft Visual C++ and Fortran Powerstation
languages version 4.0. Some testing has also been performed on a SUN workstation,
but the Matlab interface in particular could still be buggy on UNIX computers.

Version 0.1 is the code as it has been used to write the paper Improved
Numerical Floquet Multipliers (submitted to International Journal on
Bifurcation and Chaos,) though the adaptations to the AUTO97 have not been included
in the archive. If you are interested in the AUTO interface, please send e-mail
to .
Version 0.1 supports the computation of the periodic real Schur decomposition
of a matrix product G_{m}...G_{1}. Singular matrices
are allowed. The present version does not yet support the computation of eigenvectors
or the reordering of the Schur decomposition.

IMPORTANT NOTICE: the code is free for non-commercial
use. Note that every use of the code is at your own risk. I do not guarantee
that the code is bug-free or suited for your problem. This is a typical
research code and by no means a finished product. Also, if you obtain good
results, I would be glad to hear about it and to receive a copy of the
paper(s) in which the results are reported.

It has to be stressed once more that the code is still experimental and needs
more testing, in particular on UNIX workstations.

Version history:

August 15, 2000: version 0.1 publicly released. This version is still very
experimental.