python-control-announce

[Richard M. <mu...@cd...>]

Version 0.5a of the Python Control Systems Library (python-control) has been posted to SourceForge.  The main changes for this version are:

* Updated time responses functions: step_response, initial_response, impulse_response and forced_response, along with MATLAB compatible versions (step, initial, impulse, lsim).  Handles MIMO systems by allowing choice of input and output. 

* Added a phase_plot command that can be used to generate rudimentary phase portraits for 2D nonlinear systems (similar to the plots in Chapter 4 of Feedback Systems).  See examples/geneticswitch.py for an example.

* Updated many function names to be more consistent with python coding style.  So StepResponse is now step_response.  MATLAB module (control.matlab) interfaces are unaffected (continue to use 'step').

* New function to compute frequencies at which transfer function crosses real axis (phase_crossover_frequencies). Contributed by Steffen Waldherr <wal...@is...>

You can download this version of the code from SourceForge

  https://sourceforge.net/projects/python-control/files

A more detailed list of changes is included below (starting from 0.4c).

-richard

2011-08-07  Richard Murray  <mu...@ma...>

	* setup.py: updated version number; next release will be 0.5a since
	the changes in function names and argument/return value order (for
	time reponses) require small updates in code

	* examples/secord-matlab.py, examples/pvtol-nested-ss.py,
	examples/test-response.py, examples/pvtol-nested.py: fixed small bug
	in order of output arguments for step command

2011-08-06  Richard Murray  <mu...@ma...>

	* src/matlab.py (ngrid): copy documentation from nichols_grid

	* src/__init__.py: changed import commands to import specific
	functions rather than '*' (better modularity)

	* src/freqplot.py: default function names are now bode_plot,
	nyquist_plot and gangof4_plot (still with aliases to non-"_plot"
	versions)

	* src/nichols.py (nichols_plot): updated nichols to nichols_plot for
	consistency with other python-control plotting functions.  Set up
	alias for original name

	* src/margins.py: StabilityMargins, PhaseCrossoverFrequencies ->
	stability_margins, phase_crossover_frequencies

	* src/phaseplot.py: changed PhasePlot and boxgrid to phase_plot,
	box_grid 

	* src/timeresp.py: changed ForcedReponse, InitialReponse,
	ImpulseReponse and StepResponse to forced_response,
	initial_response, impulse_response and step_response.

	* src/rlocus.py: changed RootLocus to root_locus for better
	compatability with PEP 8.  Also updated unit tests and examples.

2011-07-25  Richard Murray  <mu...@ma...>

	* tests/phaseplot_test.py: updated unit tests to use new call
	signatures 

	* examples/phaseplots.py: updated calls to PhasePlot to use new
	argument structure

	* src/phaseplot.py (PhasePlot): Updated call signature to be
	more pythonic and fixed up documentation.

	* examples/genswitch.py (genswitch): added new example showing
	PhasePlot functionality

	* src/phaseplot.py (boxgrid): added function to compute initial
	conditions around the edges of a box

2011-07-24  Richard Murray  <mu...@ma...>

	* tests/margin_test.py: added simple unit tests for margin functions
	(initial versions just call functions; some comparisons missing)

	* examples/README: added missing README file

	* examples/phaseplots.py: FBS examples for phaseplot

	* tests/phaseplot_test.py: unit tests for phaseplot

	* src/phaseplot.py: initial cut at phase portrait function, built
	from amphaseplot (Feeback Systems [FBS], Astrom and Murray, 2008)

2011-07-15  Richard Murray  <mu...@ma...>

	* tests/matlab_test.py (TestMatlab): added unittest for margin()
	commands (calling format only)

	* src/statesp.py (StateSpace): updated comments

	* tests/margin_test.py: set up unit tests for StabilityMargins() and
	PhaseCrossoverFrequencies()

	* src/__init__.py: added margins.py to __init__

2011-07-14  Richard Murray  <mu...@ma...>

	* src/margins.py (GainPhaseMargin): moved freqplot.MarginPlot to
	margin.StabilityMargins (MarginPlot didn't actually plot anything)

	* src/margins.py (PhaseCrossoverFrequencies): added new function to
	compute frequencies that we cross real axis.  Contributed by Steffen
	Waldherr <wal...@is...>

2011-07-11  Richard Murray  <mu...@ma...>

	* src/rlocus.py: added real() and imag() to list of functions
	imported from numpy

	* src/freqplot.py: renamed plotting functions to BodePlot,
	NyquistPlot, GangOf4Plot and MarginPlot.  Set up aliases to the more
	common names (bode, nyquest, gangof4, margin).  Mainly playing
	around with idea for the eventual interface to use.

	* tests/matlab_test.py: updated timeresp outputs to match MATLAB

	* src/matlab.py (impulse, initial, lsim, step): switched outputs
	from step, impulse, initial, lsim to match MATLAB standard

2011-07-01  Richard Murray  <mu...@ma...>

	* src/rlocus.py: modified scipy import to only import those
	functions that we actually use.  This fixes a problem pointed out by
	Carsten Knoll (TU Dresden) where control.place could be overwritten
	by numpy.place (because of an "from scipy import *" in rlocus.py

	* doc/intro.rst: Added link to scipy web page talking about the
	differences between numpy and MATLAB (contributed by Shuo Han).

2011-06-25  Richard Murray  <mu...@ma...>

	* src/xferfcn.py (TransferFunction._common_den): changed tolerance
	for detecting complex valued poles to a user-settable parameter,
	with default value 1e-8.  This was an attempt to fix errors in the
	convert_test.py unittest script (conversion routine was
	misclassifying some poles as imaginary when they weren't).

	* src/xferfcn.py (_convertToTransferFunction): converted arguments
	to tb04ad to numpy arrays; fixes a unit test error in convert_test.py.

	* src/statefbk.py (gram): convert system matrix passed to sb03md to
	numpy array; this fixes a unit test error in modelsimp_test.py.

	* src/matlab.py (impulse): got rid of X0 argument for impulse
	response (not implemented in MATLAB).

	* doc/intro.rst: added some quick start information

	* src/matlab.py: added documentation for step, impulse, initial, lsim

	* src/timeresp.py: fixed some MATLAB specific function names in
	function doc strings

2011-06-22  Richard Murray  <mu...@ma...>

	* doc/intro.rst: fixed some small types
	
	* doc/control.tex: removed (no longer needed)

2011-06-22  Richard Murray  <mu...@ma...>

	* doc/intro.rst: Added a slightly more general introduction, with a
	pointer to the python-control wiki (on sf.net)

	* doc/Makefile: Changed path to sphinx-build to assume it is in the
	users path (as opposed to an explicit path)

	* doc/conf.py: Added release information into documentation file

2011-06-21  Richard Murray  <mu...@ma...>

	* src/statesp.py (_mimo2siso): Moved function from matlab.py.

	* src/timeresp.py: added file documentation + split out and updated
	copyright info.  Small corrections to documentation.
	(InitialResponse): Added missing transpose argument in call to
	ForcedResponse 

	* src/matlab.py: minor changes to documentation to avoid line wraps
	on standard (80 col) terminal window

	* src/matlab.py: removed time-series convention documentation from
	matlab.py since current MATLAB version uses standard conventions.
	This documentation is currently in timeresp.py.

	* src/*, doc/*: added Eike Welk's documentation modifications

2011-06-18  Richard Murray  <mu...@ma...>

	* src/timeresp.py, src/matlab.py: moved documentation about time
	series convention from matlab.py to timeresp.py

	* examples/pvtol-nested-ss.py: Fixed bug in call to step (wrong
	second argument)

	* tests/matlab_test.py: Updated tests to use MATLAB time response
	conventions.

	* tests/timeresp_test.py: Created unit tests for timeresp module,
	based on matlab_test.py

2011-06-17  Richard Murray  <mu...@ma...>

	* src/timeresp.py (ForcedResponse): swapped order of input and time
	arguments for linear response, following Eike's comment "T must
	always be supplied by the user, but U has a useful default value of
	0." 

	* src/matlab.py: moved code for lsim, initial, step, and impulse to
	timeresp.py and put in new routes that call timeresp.* versions of
	the functions with transposeData set to True.

	* src/timesim.py (_check_convert_array): added transpose argument
	that will transpose input data before processing it.

	* src/timesim.py: renamed lsim, initial, step, and impulse functions
	to ForcedResponse, InitialResponse, StepResponse and
	ImpulseResponse.  These versions use Eike Welk's input ordering.

	* examples/pvtol-nested.py: calls to step() had screwed up inputs.
	Fixed. 

2011-06-17  Richard Murray  <mu...@ma...>

	* src/matlab.py: added MIMO extensions from Eike Welk on 12 Jun
	2011: adds MIMO capabilities for ``lsim``, ``step``, ``impulse``,
	``initial`` 

	* src/matlab.py: added changes from Eike Welk on 12 May 2011:

	  - An implementation of the four simulation functions ``lsim``,
  	    ``step``, ``initial``, and ``impulse`` of the module ``matlab``. 

          - Adds a function ``dcgain`` to the ``matlab`` module, which
  	    computes the gain of a linear system for steady state and
	    constant input. 

          - The patch contains a bug fix for class ``StateSpace``, which
	    enables it to work properly together with Scipy's ``signal``
	    module.  

          - The simulation functions' return values are changed (back?) to
	    arrays, because matrices confuse Matplotlib.

	  - New times series convention: see _time-series-convention section
 	    of matlab documentation

	  - SISO simulation data are squeezed on output.  To turn this off,
	    pass the option squeeze=False