2012-11-03  Richard Murray  <murray@altura.local>

	* doc/modules.rst: updated documentation format so that items are
	broken down by functionality and not internal module name.  Still
	not complete, but most functions should now show up in documentation.

	* doc/index.rst: got rid of todos from documentation (not formatted
	correctly and shouldn't show up in user documentation)

	* src/lti.py: added missing docstrings

	* doc/intro.rst: small tweaks to text, including adding a link to FBS

2012-11-03  Richard Murray  <murray@altura.local>

	* src/rlocus.py (_RLSortRoots): convert output of range() to
	explicit list for python 3 compatability

	* tests/modelsimp_test.py, tests/slycot_convert_test.py,
	tests/mateqn_test.py, tests/statefbk_test.py: updated test suites to
	skip specific tests that require slycot if it is not installed

	* src/exception.py (slycot_check): added a function to check if
	slycot is installed

	* README: updated readme to include information about running
	nosetests, which works in python3 (unlike the test_all.py script)

	* tests/test_control_matlab.py, tests/test_all.py: set to executable
	so that nosetests does not run this file (it already runs all unit
	tests in this directory).  Add comments at top talking about tests.

	* tests/discrete_test.py (TestDiscrete.test_discrete_bode):
	explicitly create a list from map() output for python 3

	* src/frdata.py: removed long data type from comparisons for
	constant systems (not supported in python3)

	* src/xferfcn.py (TransferFunction.freqresp): force frequencies to
	be a list (map returns iterator in python3)

	* src/lti.py (isdtime, isctime): updated timebase checking since
	python3 won't allow dt to be compared to integer

	* src/__init__.py: updated frdata import to python3 compatible form

	* src/statesp.py (_convertToStateSpace): fixed exception syntax to
	be python3 compatible

	* examples/pvtol-nested.py: converted print statements to be python3
	compatible

	* doc/class_strings.rst: added FRD class to list of classes that
	show up in the user documentation

	* examples/rss-balred.py: fixed error in output argument order for
	call to matlab.impulse

	* ../README: updated readme file as a test of post-commit hook

2012-11-02  Richard Murray  <murray@altura.local>

	* doc/conf.py, setup.py: updated version number to 0.6c

	* tests/frd_test.py: unit tests for FRD data type
	(suite): added suite() function to allow test_all.py to work

	* tests/xferfcn_test.py (TestXferFcn.testMinreal): new unit test

	* src/xferfcn.py (TransferFunction.minreal): new function for
	removing cancelling pole/zero pairs, contributed by M.M. (Rene) van
	Paassen

	* src/statesp.py (_convertToStateSpace): new functionality for
	converting a matrix to a constant system

	* src/modelsimp.py (minreal): removed extraneous code (moved to
	xferfcn.py)

	* src/frdata.py: new file implementing FRD data type, contributed by
	M.M. (Rene) van Paassen

	* src/xferfcn.py: resolved conflict between versions

---- control-0.6b released -----

2012-11-02  Richard Murray  <murray@altura.local>

	* src/xferfcn.py, src/statesp.py, src/lti.py, src/bdalg.py:
	constants must now be of type 'int' rather than 'long' (for python 3
	compatibility)

	* tests/statefbk_test.py, tests/slycot_convert_test.py,
	tests/convert_test.py: added import __future__ calls for python 3
	compatibility; updated print calls

	* src/modelsimp.py, src/xferfcn.py, src/delay.py, src/phaseplot.py,
	src/margins.py, src/statesp.py, src/mateqn.py: added import
	__future__ calls for python 3 compatibility

2012-11-02  Richard Murray  <murray@altura.local>

	* src/xferfcn.py, src/timeresp.py, src/statesp.py, src/statefbk.py,
	src/robust.py, src/rlocus.py, src/pzmap.py, src/phaseplot.py,
	src/nichols.py, src/modelsimp.py, src/matlab.py, src/margins.py,
	src/freqplot.py, src/ctrlutil.py, src/bdalg.py: globally referenced
	import commands for python 3.x

	* src/__init__.py: changed import commands to be global instead of
	local ('from control.bdalg ...' instead of 'from bdalg ...')

2012-10-31  Richard Murray  <murray@altura.local>

	* src/xferfcn.py (TransferFunction._common_den): converted print
	statements to python 3 compatible form and included
	__future__.print_function

	* src/phaseplot.py: converted print statements to python 3
	compatible form and included __future__.print_function

	* src/mateqn.py (lyap, dlyap): converted except T, E to except T(E)

	* src/margins.py: converted print statements to python 3
	compatible form and included __future__.print_function

	* src/xferfcn.py (TransferFunction.__add__, __mul__, __div__,
	feedback): converted raise T, E to raise T(E) for python 3

	* src/xferfcn.py (TransferFunction.returnScipySignalLti): fixed
	raise(T(E)) bug

	* src/statesp.py (_rss_generate): fixed raise(T(E)) bug

	* src/statefbk.py (acker, gram): converted raise T, E to raise T(E) for
	python 3

	* src/modelsimp.py (hsvd, modred, balred): fixed raise(T(E)) bug and
	converted raise T, E to raise T(E) for python 3

	* src/margins.py (stability_margins): fixed raise(T(E)) bug

	* src/statesp.py: converted raise T, E to raise T(E) for python 3

	* tests/test_all.py: converted print statements to python 3
	compatible form and included __future__.print_function

	* tests/statefbk_test.py (TestStatefbk.setUp): turned off debugging
	flag (accidently left on)

---- control-0.6a released -----

2012-10-27  Richard Murray  <murray@altura.local>

	* src/statefbk.py (acker): small updates to docstring

	* src/bdalg.py (feedback): fixed up docstring formatting (for sphinx)

	* tests/statefbk_test.py (TestStatefbk.testAcker): skip
	ill-conditioned systems and loosened tolerances on acker() testing

	* src/lti.py (timebaseEqual): replaced "type(sys.dt) == NoneType"
	with "sys.dt is None", based on feedback from Luke Peterson that
	NoneType is deprecated in python 3.

2012-10-22  Richard Murray  <murray@altura.local>

	* examples/genswitch.py (genswitch): updated calls to legend, fixing
	problem pointed out by Scott Livingston

2012-10-19  Richard Murray  <murray@dn0a1594a2.sunet>

	* src/matlab.py (rlocus): reverted change in default argument
	processing for klist.  This has some negative consequences:
	http://www.deadlybloodyserious.com/2008/05/default-argument-blunders/

2012-10-18  Richard Murray  <murray@dn0a1594a2.sunet>

	* src/freqplot.py (gangof4_plot, nyquist_plot): discrete time
	systems supported (through fresp)

	* src/statesp.py (StateSpace.evalfr): added warning if discrete time
	evaluation is above Nyquist frequency

	* src/xferfcn.py (TransferFunction.evalfr, freqresp): : added
	warning if discrete time evaluation is above Nyquist frequency

	* tests/discrete_test.py (TestDiscrete.test_discrete_bode):
	rudimentary unit test for discrete bode plot

	* src/freqplot.py (bode_plot): fixed bug where input frequency list
	was being overwritten by default frequency range

	* src/xferfcn.py (TransferFunction.evalfr, freqresp): handles dtime

	* src/statesp.py (StateSpace.evalfr): handles dtime

	* src/lti.py (timebaseEqual): converted function to take systems as
	inputs instead of dt as input (also affected functions in statesp.py
	and xferfcn.py)

	* src/lti.py (timebase): timebase now returns dt instead of
	'ctime'/'dtime'

2012-10-13  Richard Murray  <murray@dn0a1594a2.sunet>

	* src/lti.py (timebase): new function to return timebase.  Doesn't
	yet handle the case where dt == None.

2012-10-07  Richard Murray  <murray@altura.local>

	* src/matlab.py (c2d): MATLAB compatible function (just calls
	sample_system)

	* tests/discrete_test.py (TestDiscrete.test_sample_system): unit
	test for sampling

	* src/dtime.py (sample_system, _c2dmatched): new functions, based on
	contributiosn from Benjamin White

	* src/dtime.py: added back this file, this time with sampling routes
	to convert from continuous to discrete time

	* src/timeresp.py (forced_response): added discrete time simulator,
	using dlsim from scipy.signal

2012-10-07  Richard Murray  <murray@altura.local>

	* doc/conf.py: fixed release number (0.6a instead of 0.6c)

	* src/__init__.py: moved timebase functions from dtime to lti

	* src/lti.py: moved isdtime, isctime, timebase, and timebaseEqual
	from dtime.py to lti.py.  Moved initialization of dt to
	Lti.__init__().

	* src/statesp.py (StateSpace.__init__): Moved dt
	initialization to Lti object initialization

	* src/xferfcn.py (TransferFunction.__init__): Moved dt
	initialization to Lti object initialization

2012-10-06  Richard Murray  <murray@altura.local>

	* tests/discrete_test.py: added additional tests for dt = True cases

	* src/statesp.py (StateSpace.__str__): show sampling time as
	'unspecified' if dt is a boolean and equal to True

	* src/xferfcn.py (TransferFunction.__str__): don't print sampling
	time (dt) if dt = True (discrete time with unspecified time base)

	* src/dtime.py: added code to support dt = True for unspecified
	sampling time for a discrete time system

	* src/bdalg.py: much -> must in docstrings

2012-10-06  Richard Murray  <murray@altura.local>

	* src/dtime.py: new module with functions for operating on discrete
	time systems

	* src/modelsimp.py: added NotImplementedError for discrete time
	* src/freqplot.py: added NotImplementedError for discrete time

	* src/bdalg.py: added documentation about timebases (discrete versus
	continuous)

	* src/statesp.py (_mimo2siso): include sampling time

	* src/xferfcn.py (TransferFunction.__str__): added optional var
	keyword to allow any symbol to be used

	* src/matlab.py (tf2ss): added code required to keep track of dt

	* src/xferfcn.py (TransferFunction.__str__): added additional string for
	discrete time system, plus use 'z' for polynomial variable
	(TransferFunction.__neg__): set sampling time for negation
	(TransferFunction.__add__): added test for same sampling time
	(TransferFunction.__mul__): added test for same sampling time
	(TransferFunction.__div__): added test for same sampling time
	(TransferFunction.feedback): added test for same sampling time

	* src/statesp.py (StateSpace.__str__): added additional string for
	discrete time system
	(StateSpace.__add__): added test for same sampling time
	(StateSpace.__mul__): added test for same sampling time
	(StateSpace.__rmul__): set sampling time for product
	(StateSpace.__neg__): set sampling time for negation
	(StateSpace.feedback): added test for same sampling time

	* tests/discrete_test.py (TestDiscrete): unit tests for discrete
	time systems

	* src/xferfcn.py (TransferFunction.__init__): added dt class
	variable for discrete time systems

	* src/statesp.py (StateSpace.__init__): added dt class variable for
	discrete time systems

---- control-0.5c released -----

2012-10-03  Richard Murray  <murray@altura.local>

	* tests/matlab_test.py (TestMatlab.testSsdata): unit test

	* src/matlab.py (ssdata, tfdata): new functions to return state
	space and transfer function object data.  For transfer functions,
	currenly requires SISO system

	* src/freqplot.py (bode_plot):  Adding np.atleast_1d to the
	np.squeeze calculations makes it possible to use a single value
	frequency list (contributed by Benjamin White)

2012-09-09  Richard Murray  <murray@altura.local>

	* tests/statefbk_test.py (TestStatefbk.testAcker): unit test

	* src/statefbk.py (acker): added acker() from Roberto Bucher.

2012-08-29  Richard Murray  <murray@altura.local>

	* src/xferfcn.py (TransferFunction._common_den): fixed up code for
	case where poles have multiplicity > 1.  Set end limits of check to
	avoid overruning the list + combine complex conjugate pole pairs
	from the outside in to prevent small errors from growing.

2012-08-26  Richard Murray  <murray@altura.local>

	* tests/convert_test.py (TestConvert.testConvert): replaced previous
	test of transfer function coefficients with a frequency response
	test.  This is necessary because various degenerate conditions will
	generate a situation where the transfer functions are of different
	forms but still equal.  Eg 0/1 = 1e-17 s + 1e-16 / (s^2 + s + 1).
	Still getting errors, but looks like actual problem in conversion.

	* src/statesp.py (_mimo2siso): set default value for warn_conversion
	to False

	* tests/convert_test.py (TestConvert.testConvert): Added check to
	make sure that we don't create problems with uncontrollable or
	unobservable systems.

2012-08-25  Richard Murray  <murray@altura.local>

	* src/xferfcn.py (TransferFunction._common_den): identified bug in
	the way that common denominators are computed; see comments in code
	regarding complex conjugate pairs.

	* src/statefbk.py (place): repalced nd.size(placed_eigs) with
	len(placed_eigs) to fix intermittent problems pointed out by Roberto
	Bucher in control-0.3c.

	* tests/rlocus_test.py (TestRootLocus.testRootLocus): added sort()
	to test to get rid of problems in which ordering was generating an
	error.

	* src/freqplot.py (nyquist_plot): added code from Kevin Davies to
	label frequency points in Nyquist plot

	* src/__init__.py: import non-conflicting MATLAB functions by default

	* src/freqplot.py (bode_plot, nyquist_plot): simplified code and
	removed unneeded options.  To set color, linestyle, etc use keywords
	and pass to matplotlib.

2012-08-24  Richard Murray  <murray@altura.local>

	* src/freqplot.py: added in plot enhancements from Kevin Davies
	(bode_plot): pass optional arguments and keywords to matplotlib
	(get_pow1000): new function for determinine engineering exponent
	(gen_prefix): new function to get SI prefix for power of 1000

	* src/freqplot.py (bode_plot): removed extraneous phase_deg calculation

2012-01-07  Richard Murray  <murray@malabar.local>

	* doc/modules.rst: added new sections for analysis, synthesis,
	frequency plots and time response.

	* doc/index.rst (Contents): added modules and examples.

	* src/xferfcn.py (_convertToTransferFunction): added check for
	slycot import error.  If not present, use signal.lti to perform the
	conversion.  Only works for SISO.

	* src/statesp.py (_convertToStateSpace): added check for slycot
	import error, to allow basic functionality without the presence of
	slycot (contributed by Ryan Krauss).

	* tests/slycot_convert_test.py (TestSlycot.testTF): moved slycot
	import into test function, so that test script still works even if
	time response is not present.

2011-08-09  Richard Murray  <murray@malabar.local>

	* src/timeresp.py: fixed doc reference to time-series-convention

2011-08-08  Richard Murray  <murray@malabar.local>

	* doc/index.rst, doc/modules.rst: Moved MATLAB section into
	python-control modules file

2011-08-07  Richard Murray  <murray@malabar.local>

	* doc/conf.py: added autosummary extension

	* doc/timeresp.rst: New file containing listing of functions for
	time responses (step, initial, etc)

	* doc/freqplot.rst: New file listing functions for frequency
	plots (bode, nyquist, etc)

	* doc/modules.rst: New file that contains a listing of the major
	modules in the toolbox

	* doc/index.rst (Contents): Rearranged contents to put modules
	documentation in a separate section.  Also added examples section
	(not quite ready yet).

2011-08-07  Richard Murray  <murray@malabar.local>

	* examples/rss-balred.py: reordered outputs from call to matlab.step
	(missed this the first time around)

	* doc/matlab_strings.rst: Matlab -> MATLAB (proper spelling)

	* setup.py, doc/conf.py: updated version to 0.5b

2011-08-07  Richard Murray  <murray@malabar.local>

	* doc/conf.py: Updated version numbers to 0.5a, regenerated
	documentation and reposted on web (note that 0.5a tag and source
	distribution have this wrong)

---- control-0.5a released -----

2011-08-07  Richard Murray  <murray@malabar.local>

	* 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  <murray@malabar.local>

	* 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  <murray@malabar.local>

	* 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  <murray@malabar.local>

	* 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  <murray@malabar.local>

	* 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  <murray@malabar.local>

	* 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 <waldherr@ist.uni-stuttgart.de>

2011-07-11  Richard Murray  <murray@malabar.local>

	* 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  <murray@malabar.local>

	* 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  <murray@malabar.local>

	* 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  <murray@malabar.local>

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

2011-06-22  Richard Murray  <murray@malabar.local>

	* 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  <murray@malabar.local>

	* 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  <murray@malabar.local>

	* 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  <murray@malabar.local>

	* 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  <murray@malabar.local>

	* 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

---- control-0.4c released -----

2011-06-17  Richard Murray  <murray@dhcp096.fhl.washington.edu>

	* examples/tfvis.py: Added tfvis, Simple GUI application for
	visualizing how the poles/zeros of the transfer function effects the
	bode, nyquist and step response of a SISO system.  Contributed by
	Vanessa Romero Segovia, Ola Johnsson, Jerker Nordh.

2011-06-16  Richard Murray  <murray@malabar.local>

	* src/matlab.py: import mateqn functions

	* src/__init__.py: import mateqn functions

	* tests/test_all.py: added unit tests for matrix solvers, converting
	to standard format along the way.  Seems to work even if slycot
	routines are not in place, but I'm not sure if this is for the right
	reasons...

	* src/mateqn.py: added matrix solvers from LTH (Ola Johnsson, Jerker
	Nordh, Bjorn Olofsson, Vanessa Romero).  Moved slycot function
	checks to the portion of the code where they are used, so that
	missing slycot doesn't mess up initialization if proper version of
	slycot is not available.

2011-04-02  Richard Murray  <murray@malabar.local>

	* src/xferfcn.py (TransferFunction.__add__): fixed bug when adding a
	transfer function to state space system; _convertToTransferFunction
	was being called with input/output keywords.  Picked up in unit test.

	* tests/matlab_test.py: added calls to all of the functions that are
	currently implemented in the library, to make sure there are no
	hidden issues.  These calls do *not* test functionality, they just
	make sure that MATLAB compatibility functions accept the right types
	of arguments.

	* examples/secord-matlab.py: added root locus plot to list of
	figures that are produced

	* src/__init__.py: added rlocus to list of modules that are imported
	by control module

	* src/exception.py (ControlMIMONotImplemented): added exception for
	functions that are not yet implemented for MIMO systems

	* src/xferfcn.py (TransferFunction.__init__): convert integer
	numerator and denominator objects to floats to eliminate errors when
	creating common denominator (also used on pole command).  This fixes
	and error were tf([1], [1, 2, 1]).pole() would generate an error.

	* src/freqplot.py (bode): Tweaked documentation string to remove 'h'
	from mag and phase return arguments

	* src/rlocus.py (RootLocus): removed commands that set figure number
	inside of RootLocus command, for consistency with other frequency
	plot routines.  Added Plot=True argument and updated documentation.

	* src/matlab.py: added rlocus() command (calls RootLocus)

	* MANIFEST.in: Added MANIFEST.in file to include examples and tests
	in source distribution

	* README: Updated to include information on how to run unit tests.

	* setup.py: updated version number to 0.4c

---- control-0.4b released -----

2011-04-02  Richard Murray  <murray@malabar.local>

	* src/__init__.py: removed import of tests module (moved to tests/)

	* src/matlab.py: Added hsvd, balred, modred to list of functions
	that are imported for use as is.  Updated documentation string to
	indicate that these are implemented, along with a few other
	functions (zero, lqr) that weren't properly listed.

	* src/modelsimp.py (balred): Removed extraneous print statements
	(modred): Set method to be 'matchdc' by default (to match MATLAB)

	* src/__init__.py: added missing import of modelsimp functions

	* tests/slycot_convert_test.py (TestSlycot.testTF): turned off print
	statements in unit test to make it easier to see results.  Use
	verbose=True to turn back on.

	* tests/convert_test.py (TestConvert.testConvert): got rid of print
	statements in unittest; clutters the output so that you can't see
	the errors clearly.  Use verbose=True to turn back on.

	* src/statesp.py (_convertToStateSpace): removed "buggy" print
	statements 

	* src/xferfcn.py (_convertToTransferFunction): removed "buggy" print
	statements 

	* tests/nichols_test.py (TestStateSpace.testNgrid): updated testcode
	to turn off grid in initial Nichols chart plot.

	* src/freqplot.py: updated comments at top of file to reflect
	nichols chart move

	* src/nichols.py: transferred over changes from v0.3d

	* src/matlab.py (ngrid): moved import to function

2011-03-31  Richard Murray  <murray@malabar.local>

	* examples/pvtol-nested.py: updated stability margin plot to use
	proper calling format for bode().

	* src/statesp.py (_convertToStateSpace): moved slycot import
	to the location where it is actually needed (allows running some
	commands without slycot installed)

	* src/xferfcn.py (_convertToTransferFunction): moved slycot import
	to the location where it is actually needed (allows running some
	commands without slycot installed)

	* src/nichols.py: new file for Nichols plot routines; move
	nichols(), nichols_grid(), closed_loop_contours(), m_circles(),
	n_circles()

	* src/__init__.py, src/freqresp.py, src/matlab.py: updated to match
	new file structure for Nichols charts

	* src/nichols.py (nichols): updated processing of freqresp to take
	into account the fact that return arguments are now a matrix of
	results (even for a SISO system)

2011-03-30  Richard Murray  <murray@malabar.local>

	* tests/: added top level subdirectory, to be used for unit tests.
	The idea in putting the code here is that you can do 'setup.py test'
	during installation to make sure everything is working correctly.
	The test code would normally *not* be callable from the installed
	module. 

	* tests/*_test.py: moved from src/Test*.py

	* setup.py: updated version number.

2011-02-13  Richard Murray  <murray@sumatra.local>

	* src/*.py: added svn:keywords Id properly

	* src/matlab.py (ngrid): added ngrid() from v0.3d

	* src/freqplot.py (nichols_grid, closed_loop_contours, m_circles,
	n_circles): copied over changes from Allan McInnes in v0.3d; ngrid()
	functiality + split out some of the nichols chart code into separate
	functions

2011-02-12  Richard Murray  <murray@sumatra.local>

	* setup.py: updated version number to 0.4a

2010-11-05  Richard Murray  <murray@sumatra.local>

	* external/yottalab.py: New file containing Roberto Bucher's control
	library functions.  OK to start pulling these into the main library,
	with attribution, but note that they use modifications of the
	default library => some rewrites will be needed.

2010-09-11  Richard Murray  <murray@sumatra.local>

	* src/matlab.py (step): Added local step response function that uses
	lsim2() instead of signal.step (which can't handle integrators).
	This function may not be needed when new scipy step2() function is
	available.
	(impulse): Added local impulse response function that sets the
	initial condition based on the input matrix and then uses the
	lsim2() function to compute the response.

	* examples/test-response.py: Added test script for making sure that
	time repsonse functions are working as desired

	* src/matlab.py (lsim): Added local version of lsim that calls
	signal.lsim2 (actual ODE integrator)

2010-09-06  Richard Murray  <murray@sumatra.local>

	* src/statefbk.py (ctrb): new function for testing controllability
	* src/statefbk.py (obsv): new function for testing observabiilty

2010-09-02  Richard Murray  <murray@sumatra.local>

	* src/statefbk.py (place): Use np.size() instead of len() for
	finding length of placed_eigs for better compatability with
	different python versions [courtesy of Roberto Bucher]

	* src/delay.py (pade): New file for delay-based computations +
	initial implementation of pade() [courtesy Sawyer Fuller]

2010-06-17  Richard Murray  <murray@sumatra.local>

	* src/rlocus.py: changed num, den to nump, denp for clarity
	* src/rlocus.py: new file with Ryan Krauss's root locus code

2010-06-06  Richard Murray  <murray@sumatra.local>

	* examples/pvtol-lqr.py: Added example to test out LQR routines

	* src/matlab.py (bode): created a wrapper that allows MATLAB style
	arguments for bode (eg, bode(sys1, sys2))

	* src/ctrlutil.py (issys): added new function to check if an object
	is a system (state space or transfer function).  Will generalize
	this latter to look for other compatible classes.

	* src/freqplot.py (bode): Compute frequency range of bode plot based
	on poles and zeros
	(bode): Allow bode plot to be passed a list (or tuple) as the first
	argument, in which case multiple bode plots are generated

	* src/statesp.py (StateSpace.zeros): new function to compute zeros
	for a state space system
	(StateSpace): defined new functions to compute poles of a state
	space system

	* src/xferfcn.py (TransferFunction): defined new functions to
	compute poles and zeros of a transfer function.

2010-05-31  Richard Murray  <murray@sumatra.local>

	* src/exception.py (ControlNotImplemented): added new exception, to
	be used for functions that are not yet implemented

	* src/statefbk.py (lqr): added lqr function (using slycot).  Still
	needs to be verified to make sure calculations are correct.

	* ChangeLog: converted to standard GNU formation (old style below)
	* setup.py: updated package number to v0.3, changed URL to
	sourceforge wiki

------------------	
31 May 2010, RMM: added place() function using slycot
  * New module: statefbk - functions to design state feedback controllers
  * Uses Enrico Avventi slycot wrappers (http://github.com/avventi/Slycot)
  * Also added some exception types: ControlSlycot and ControlDimension
  * Added new example to test slycot interface (directly)

29 May 2010, RMM: updated function documentation
  * Added __doc__ strings for all current functions
  * Added __doc__ string to matlab module, listing control toolbox functions

22 May 2010, RMM: tweaked comments and released v0.3a
  * Changed copyright information on modified files to 2010
  * Updated "to do" comments to use "#! TODO:" as prefix

11 Feb 2010, GR: implemented and tested state space feedback
15 Jan 2010, GR: added new example, improved bode

4 Jan 2010, GR: updated bode plots
  * made bode plot more like matlab
  * added options for plotting in dB, Hz

27 Dec 2009, GR: important bug fix: feedback TFs were being divided by two
  
10 Oct 09, RMM: reset matplotlib import in secord-matlab
  * Using 'from matplotlib import *' causes error with figures
  * On my other computer, got error when trying to import 'matplotlib.pyplot'
  * Need to sort out versions and figure out proper import structure

13 Sep 09, RMM: added basic state space functionality
  * Updated StateSpace routines to allow BD algebra with constants
  * Updated pvtol-nested example to try to use state space representation
    (not completely working yet)

12 Sep 09, RMM: code restructuring for transfer functions
  * Implemented feedback() method in bldalg; partially working
    for mixture of TF, SS and numbers (not thoroughly tested yet)
  * New feedback method for TransferFunctions
  * Updated gangof4 to use new feedback function

9 Sep 09, RMM: updated pzmap to generate a plot (turn off with Plot=False)

8 Sep 09, RMM: rewrite of xferfcn to handle type casting better
  * Appropriate functions now call convertToTransferFunction
  * Restricted transfer function to SISO only

7 Sep 09, RMM: additional fixes
  * Implemented block diagram operations for SISO transfer functions
  * Modified frequency response functions for transfer functions
  * Added rudimentary pole/zero computations
  * Added comments on things that need to be fixed (search for !)

5 Sep 09, RMM: updates to get standard examples working
  * Copied and converted pvtol_nested.py from AM08, Chapter 11
  * Updated freqresp to use poly1d for computing values
  * Added outputs to bode plot - return mag and phase subplot handles

2009-05-24  Richard Murray  <murray@kona-2.local>
  * ./ Initial creation of package files and ChangeLog
  * Using simpler text format since emacs python mode doesn't support
    ChangeLog entries anyway


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