[SciPy-Dev] ltisys.py

josef.pktd@gmai... josef.pktd@gmai...
Sat Aug 21 14:09:36 CDT 2010

On Sat, Aug 21, 2010 at 2:00 PM, Roberto Bucher <roberto.bucher@supsi.ch> wrote:
> I'm working on a control system toolbox for python. In particular I've modified
> some functions of the control system toolbox developed by Richard Murray and I
> added some new functions.  The first problem is related to the modul ltisys.py
> that I modified for handling:
> - MIMO systems (state-space only)
> - Sampling Time for discrete time system
> I've done other modifications to different modul of Richard, who is in CC:
> - matlab.py
> - statesp.py
> - xferfcn.py
>  in order to implement the following new functions in my yottalab.py modul:
> - c2d (zoh+bilinear)
> - d2c (zoh+bilinear)
> - dare - discrete riccati solution
> - care - continous riccati solution
> - dlqr - discrete linear quadratic regulator
> - ctrb - controllability matrix
> - acker - ackerman pole placement
> - minreal - minimal state space representation
> - dcgain steady state gain for both continous and discrete time systems
> - tf (casting function)
> - ss (casting function)
> The modified files can be downloaded from my homepage
> in the python section, but I want to see how I can contribute to put the
> modifications in the main Scipy distribution.

I would find it very good if such enhancements go into scipy ltisys.
It was often requested, and I think we will be able to use them also
for time series analysis. I stopped looking at it after I figured out
ltisys only handled single input, mainly continuous time processes.
And I hope someone finds the time soon to review this (but
unfortunately I don't have any time at all right now).

A few questions:

Do you have your changes under version control? It would make it
easier to produce a diff and look at the changes.

Do you have examples that could be converted into tests?

scipy and python-control are BSD
your yottalab.py doesn't have a license statement, but it has to be
GPL by infection, because of
"from slycot import sb02od, tb03ad"  since slycot is GPL

Would it be useful to license your parts of yottalab that don't rely
on slycot as BSD?
e.g. if a replacement for slycot could be found.

or maybe python control also moves to GPL with slycot integration ?



> Best regards
> Roberto
> --
> -----------------------------------------------------------------------------
> Coltivate Linux! Tanto Windows si pianta da solo...
> -----------------------------------------------------------------------------
> University of Applied Sciences of Southern Switzerland
> Dept. Innovative Technologies
> CH-6928 Lugano-Manno
> http://web.dti.supsi.ch/~bucher
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