--- /dev/null
+Summary of important user-visible changes for releases of the control package
+
+===============================================================================
+control-2.3.52 Release Date: 2012-06-25 Release Manager: Lukas Reichlin
+===============================================================================
+
+** Fixed a silly mistake in MIMO transfer function to state-space conversion.
+ The bug has been introduced with control-2.3.51.
+ (Thanks to Jim Rawlings for providing the test case)
+
+** dlqe, lqe
+ Added new functions for linear quadratic estimators.
+ (Thanks to Megan Zagrobelny)
+
+** Upon request of the Debian maintainers, the tex-files control.tex and
+ functions.texi for generating control.pdf are included in the doc folder,
+ next to control.pdf. Note that functions.texi is generated automatically
+ by the scripts in the control/devel folder and the package generate_html.
+ They are not included in the control package and can be found on the
+ OctaveForge SVN server.
+
+** Minor improvements in various help texts.
+
+
+===============================================================================
+control-2.3.51 Release Date: 2012-06-03 Release Manager: Lukas Reichlin
+===============================================================================
+
+** filt, filtdata, tf
+ -- Added function "filt" to specify disrete-time transfer functions in DSP
+ format, i.e. z^-1.
+ -- Added function "filtdata" to return any type of discrete-time LTI model
+ in DSP format.
+ -- tf models have a new property "inv". To display a discrete-time TF sys
+ in z^-1, set sys.inv=true. In order to switch to z, set sys.inv=false.
+ "filt" sets property "inv" to true (z^-1) by default, while "tf" uses
+ false (z) as default value.
+
+** ctranspose
+ Conjugate transpose or pertransposition of LTI objects.
+ Used by Octave for "sys'". For a transfer-function matrix G, G' denotes the
+ conjugate of G given by G.'(-s) for a continuous-time system or G.'(1/z) for
+ a discrete-time system. The frequency response of the pertransposition of G
+ is the Hermitian (conjugate) transpose of G(jw),
+ i.e. freqresp (G', w) = freqresp (G, w)'.
+ WARNING: Do NOT use this for dual problems, use the transpose "sys.'"
+ (note the dot) instead.
+
+** test_control
+ Add a few remarks to the help text regarding the severity of failing tests.
+
+** Makefile fixed to work with non-standard linker options e.g on
+ Apple.
+
+** The conversion to state-space of multi-input transfer functions with common
+ row denominators is now handled more efficiently.
+
+
+===============================================================================
+control-2.3.50 Release Date: 2012-03-06 Release Manager: Lukas Reichlin
+===============================================================================
+
+** Added new functions for frequency-weighted model and controller order
+ reduction:
+
+ bstmodred btaconred
+ btamodred cfconred
+ hnamodred fwcfconred
+ spamodred spaconred
+
+** Anderson, Madievski
+ -- Added two examples for controller reduction. The m-files are named after
+ the authors of the corresponding papers.
+
+** fitfrd
+ -- Added function to fit frequency response data with a state-space model.
+
+** set
+ -- The set command doesn't need a return argument anymore in order to save
+ the modified values. set (sys, "key", value) is now equivalent to
+ sys = set (sys, "key", value).
+
+** Require Octave version 3.6.0 or better. (The frequency response plotting
+ commands have been simplified. They now use the fixed "axis tight" command.
+ This is a first step towards multiple systems in one plot,
+ e.g. bode (sys1, sys2, sys3). Furthermore, the code takes advantage of the
+ new "arrayfun" function which became a faster oct-file instead of an m-file)
+
+** Revised package installation and cleanup efforts under the hood.
+ The new solution compiles the SLICOT library in a less barbaric way and
+ creates only a single oct-file containing all the SLICOT routines.
+ This also brings along faster compile times.
+ (Special thanks to Hans Buchmann, Carlo De Falco and Michael Goffioul for
+ their advice)
+
+** doc/control.pdf
+ -- Extended PDF manual.
+
+
+===============================================================================
+control-2.2.5 Release Date: 2012-02-09 Release Manager: Lukas Reichlin
+===============================================================================
+
+** Improved Matlab compatibility for frequency response commands. It is now
+ possible to specify a frequency range. Example: bode (sys, {wmin, wmax})
+ where wmin and wmax denote frequencies in rad/s.
+
+** margin
+ -- Fixed a variable name such that discrete-time models are plotted
+ without an error. (Thanks to Renato Caldas)
+
+
+===============================================================================
+control-2.2.4 Release Date: 2012-01-07 Release Manager: Lukas Reichlin
+===============================================================================
+
+** Compatibility with Octave 3.6.0. (The makefile must specify the libraries
+ that mkoctfile needs to link. Thanks to Marco Atzeri and Carlo De Falco)
+
+** ctrbf, obsvf
+ -- Added new functions to compute controllable and observable block
+ Hessenberg realizations based on SLICOT TB01UD.
+ (Thanks to Benjamin Fernandez and Alexandre Felipe)
+
+
+===============================================================================
+control-2.2.3 Release Date: 2011-12-07 Release Manager: Lukas Reichlin
+===============================================================================
+
+** Improved performance when computing the frequency response of transfer
+ function models by orders of magnitude. (I realized that "polyval" can
+ evaluate a polynomial at several values at once in a vectorized manner.)
+
+** bode, bodemag, nichols, sigma
+ -- Fixed a hang when plotting pairs of purely imaginary poles or zeros.
+ The hang was caused by nonsensical (Inf, NaN) axis values.
+ (Reported by Laurent Tissier)
+
+** Use single instead of double quotes when displaying names of TF and FRD
+ models.
+
+
+===============================================================================
+control-2.2.2 Release Date: 2011-12-04 Release Manager: Lukas Reichlin
+===============================================================================
+
+** Improved error messages for place, ARE solvers and robust control commands.
+
+** minreal, ss
+ -- Fixed a crash for descriptor models. minreal for dss models as well as
+ conversion from non-proper transfer functions to descriptor state-space
+ models should work now as expected.
+
+** ss
+ -- Revised default tolerance for transfer function to state-space conversion
+ by SLICOT TD04AD.
+
+** Better performance when computing the frequency response of SISO transfer
+ function models.
+
+** Reorganized tests. Most tests have been moved from "ltimodels" to the files
+ of the LTI methods being tested. All available tests can be executed by
+ "test_control".
+
+** The NEWS file is handled correctly when using Octave version 3.6.
+ Type "news("control")" or "news control" to display the news (3.6 only).
+
+
+===============================================================================
+control-2.2.1 Release Date: 2011-10-24 Release Manager: Lukas Reichlin
+===============================================================================
+
+** tf
+ -- Fixed a nasty bug that prevented shortening of numerator and denominator
+ polynomials consisting solely of zeros.
+ -- MIMO support for descriptor state-space to transfer function conversion.
+ Usage: tf_sys = tf (dss_sys)
+ -- MIMO support for interconnections of non-proper transfer functions via
+ internal conversion to state-space.
+
+** ss
+ -- Support conversion from non-proper transfer function to descriptor state-
+ space. Usage: dss_sys = ss (tf_sys)
+
+** c2d, d2c
+ -- Support bilinear transformation of descriptor state-space models.
+
+** inv
+ -- Support the inversion of MIMO transfer functions. Inverses of 2x2 TFs are
+ computed directly, larger models are computed internally in state-space.
+
+** place
+ -- Return the number of fixed, assigned and uncontrollable poles in a single
+ "info" struct instead of three individual output arguments.
+
+** rlocus
+ -- Clarify usage statement in help string.
+ -- Check whether system is SISO.
+
+** MDSSystem
+ -- Display bode plots of controllers instead of singular value plots of the
+ closed loops.
+
+** hsvd
+ -- Added option "alpha" to specify the alpha-stability boundary for the
+ eigenvalues of the state dynamics matrix A.
+
+** isctrb, isobsv
+ -- Return number of controllable/observable states as a second output
+ argument.
+
+** doc/control.pdf
+ -- Added preface to PDF manual.
+
+
+===============================================================================
+control-2.2.0 Release Date: 2011-09-26 Release Manager: Lukas Reichlin
+===============================================================================
+
+** ss
+ -- Transfer function to state-space conversion uses now SLICOT TD04AD.
+ Conversion of MIMO models is now supported. Usage: ss_sys = ss (tf_sys)
+
+** tf
+ -- Support for interconnections of MIMO transfer functions. This is done by
+ an internal conversion to a minimal state-space representation. With the
+ current tf2ss and ss2tf conversions, only proper transfer function are
+ supported. This limitation does not exist for SISO transfer functions.
+ -- Fixed a cellfun statement that caused problems on MinGW32 builds and
+ possibly some others. (Reported by Bernhard Weller)
+
+** pole, zero
+ -- Computation of poles and zeros of MIMO transfer functions is now possible
+ via conversion to state-space. Please note that the state-space
+ realization of SLICOT TD04AD is a minimal one. Therefore certain poles
+ and zeros might be missing.
+
+** zpk, zpkdata
+ -- Included wrappers that create transfer function models from zero-pole-gain
+ data (zpk) and zero-pole-gain data from lti models (zpkdata). They are
+ stop-gap measures for compatibility until ZPK models are implemented.
+
+** tfdata
+ -- "vector" option added. For SISO models, it returns numerator and
+ denominator directly as column vectors instead of cells containing a
+ single column vector.
+
+** doc/control.pdf
+ -- Revised PDF manual.
+
+
+===============================================================================
+control-2.1.55 Release Date: 2011-09-07 Release Manager: Lukas Reichlin
+===============================================================================
+
+** c2d
+ -- Support for "tustin" and "prewarp" method added.
+ -- Transfer functions are now supported via the state-space methods.
+ -- Improved Texinfo string.
+
+** d2c
+ -- Discrete to continuous-time conversion added. However, support is
+ limited to the zero-order hold, tustin and pre-warping methods.
+
+** Conversion from descriptor to regular state-space is now performed by SLICOT
+ routine SB10JD. Better numerical results are to be expected over the
+ previous naive inversion formula. This conversion is used internally for
+ ssdata and some other functions.
+
+
+===============================================================================
+control-2.1.54 Release Date: 2011-08-22 Release Manager: Lukas Reichlin
+===============================================================================
+
+** tf
+ -- State-space to transfer function conversion uses now SLICOT TB04BD.
+ Conversion of MIMO models is now supported. Usage: tf_sys = tf (ss_sys)
+ -- Display an empty line between title and numerator for better readability.
+ -- Display whether model is static, continuous- or discrete-time.
+
+** A PDF manual is included for the first time. It is located inside the "doc"
+ folder. It has been generated automatically from the Texinfo help strings
+ and is not yet completely sorted out.
+
+
+===============================================================================
+control-2.1.53 Release Date: 2011-08-08 Release Manager: Lukas Reichlin
+===============================================================================
+
+** ncfsyn
+ -- Added support for McFarlane/Glover loop shaping design procedure.
+ "ncfsyn" stands for Normalized Coprime Factor Synthesis.
+
+** MDSSystem
+ -- Added example script which demonstrates the usage of the robust control
+ commands "mixsyn" and "ncfsyn".
+
+** Texinfo help strings of several functions have been extended, although
+ documentation still leaves a lot to be desired.
+
+
+===============================================================================
+control-2.1.52 Release Date: 2011-07-27 Release Manager: Lukas Reichlin
+===============================================================================
+
+** hsvd
+ -- Use scaling unless state-space model property "scaled" is set to true.
+
+** norm
+ -- Use scaling for computation of L-infinity norm unless state-space model
+ property "scaled" is set to true.
+
+** minreal
+ -- Use scaling for state-space and descriptor state-space models unless
+ property "scaled" is set to true.
+ -- More accurate results are to be expected for descriptor state-space
+ models by performing only those reduction phases where effective order
+ reduction occurs. This is achieved by saving the system matrices before
+ each phase and restoring them if no order reduction took place.
+
+** zero
+ -- Use scaling for state-space and descriptor state-space models unless
+ property "scaled" is set to true.
+
+** frdata
+ -- The frequency response is now returned correctly as an array and not as a
+ vector, unless the "vector" option is set and the system is single-input
+ single-output.
+ -- Added help text.
+
+
+===============================================================================
+control-2.1.51 Release Date: 2011-07-21 Release Manager: Lukas Reichlin
+===============================================================================
+
+** frd
+ -- Support for Frequency Response Data (frd) measurement "models".
+
+
+===============================================================================
+control-2.1.50 Release Date: 2011-07-06 Release Manager: Lukas Reichlin
+===============================================================================
+
+** ss
+ -- Support for property "scaled". By default, it is set to "false".
+
+** prescale
+ -- Scaling for state-space models (SLICOT TB01ID) and descriptor models
+ (SLICOT TG01AD).
+
+** freqresp
+ -- Scale state-space models using @lti/prescale.m if property "scaled" is
+ set to "false". Frequency response commands now perform automatic
+ scaling unless model property "scaled" is set to "true".
+
+
+===============================================================================
+control-2.0.2 Release Date: 2011-03-18 Release Manager: Lukas Reichlin
+===============================================================================
+
+** lsim
+ -- Fixed a logical error that refused valid initial state vectors. It was
+ due to a thinko introduced with the changes in control-2.0.1.
+ (Thanks to Rob Frohne)
+
+
+===============================================================================
+control-2.0.1 Release Date: 2011-03-06 Release Manager: Lukas Reichlin
+===============================================================================
+
+** lsim
+ -- Support time vectors not starting at zero. (Thanks to Rob Frohne)
+ -- Improved help text.
+
+** zero
+ -- The gain of descriptor state-space models is now computed correctly.
+ (fingers crossed)
+
+
+===============================================================================
+control-2.0.0 Release Date: 2011-02-08 Release Manager: Lukas Reichlin
+===============================================================================
+
+** First official release.
+
+
+===============================================================================