psSchur 0.1

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 Gm...G1. 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:

Version 0.1 of the code is available in 2 formats: a zip archive for Windows systems (using the MSDOS conventions for text files) and a gzipped tar archive for UNIX systems (using just a LF at the end of a line.) The archives can be downloaded using the URLs and

As I have no longer a research-oriented job, I cannot offer any support for the code.

See my homepage for contact information.