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Summary of important user-visible changes for releases of the control package =============================================================================== control-3.0.0 Release Date: 2015-10-30 Release Manager: Lukas Reichlin =============================================================================== ** Substantial parts of the most vital internals have been rewritten and streamlined in order to improve compatibility and reliability. These changes to the codebase also result in better error handling in many situations and facilitate the integration of new features in upcoming releases. ** While many issues and pitfalls existing in previous releases of the control package have been fixed, the author isn't aware (at release date) of any regressions one might expect from a x.0.0 release. Note that the absence of regressions doesn't mean the absence of bugs. Especially it doesn't mean that *all* bugs from control-2.8.5 have been fixed. Also note that to err is human, and software is written by humans. Therefore, any larger piece of software is likely to contain bugs. But the author is confident that he squashed considerably more bugs than he introduced in this release. So if you waver between updating now and waiting for control-3.0.x, the author's suggestion is definitely to update now. ** As always, your feedback is highly appreciated! Even if you think that the control package is "fubar". If you just follow the German saying "gesehen, gelacht, geloescht" - which roughly translates into "seen it, laughed at it, deleted it" - there's only little chance for improvement! So if you think you've found a bug, please take the time to report your findings on Octave's bugtracker: <http://savannah.gnu.org/bugs/?group=octave> See the link below for more information about how to report problems: <http://octave.org/bugs.html> ** Your help is welcome! There are many ways you can help the project fix the remaining problems, complete the documentation, and improve the overall user experience for both novices and experts alike. The author is aware of the fact that the documentation still leaves a lot to be desired. As it is often the case with developers, writing documentation and tutorials is neither his key skill nor his favorite occupation. After all, the author wrote the control package due to his personal interest in the field of control systems and not to make a living out of it. The developer's profits are the insights and experience he obtained from his work. Consequently, the control project doesn't ask you for money. In case you like the control package and should feel like donating, then consider donating to GNU Octave or the Free Software Foundation according to the information on their websites. Thank you! ** LTI models in general Improved handling of key-value pairs in all constructors for LTI models: tf (matrix, 'key1', val1, ...), ss (a, b, 'key1', val1, ...) Support inheritance of LTI properties in many variations: tf (num, den, ltisys), ss (a, b, ltisys, 'key1', val1, ...) sys.lti = ltisys, zpk (z, p, k, Ts, 'var', 'q', 'lti', ltisys, ...) Accept [] as an alias for unspecified sampling time (Ts = -1): filt ('q^-1', []), ss (a, b, c, d, []), sys.Ts = [] Automatic vector expansion for input and output names: sys.inname = 'str', sys.outname = '' (for MIMO systems) ** dss Fixed a long-standing but undiscovered bug where 'dss (sys)' overwrites sys.e with an identity matrix even if sys.e was not empty. D'oh! ** ss Support for the following special cases has been added: ss (sys, 'explicit') % convert descriptor system to regular one ss (sys, 'minimal') % equivalent to minreal (ss (sys)) ** tf, zpk, filt Restrict transfer function variable to the candidates 's', 'p' for continuous-time and 'z', 'q', 'z^-1', 'q^-1' for discrete-time models. s = tf ('s'), z = tf ('z^-1', Ts), tf (num, den, Ts, 'var', 'q') Previous control versions supported any string, which could be quite misleading, see bug #45371. <http://savannah.gnu.org/bugs/?43586> ** bode, bodemag, nichols, nyquist, sigma Fixed bug #42495. <http://savannah.gnu.org/bugs/?42495> It is now possible to specify a frequency vector of length 1, e.g. [mag, phase] = bode (sys, 1) Furthermore, the functions raise an error or warning if invalid arguments are passed to them. Previously, invalid arguments were simply ignored, which could be confusing. ** step, impulse, initial, ramp The time response functions now raise an error or warning if invalid arguments are passed to them. As it was the case for frequency response functions, they used to simply ignore invalid arguments. ** lsim Fixed bug #46247. <http://savannah.gnu.org/bugs/?46247> (Reported by Lutz Mager and Piet Wertelaers) Support logical arrays as input signal. Before, logical arrays were simply ignored without notice, which could lead to unexpected results. Additionally, lsim received the same improvements as the other time and frequency response functions regarding invalid arguments. ** pzmap Improved argument checks. ** augstate New function for state-space models. Adds the state vector to the output vector. ** connect The function no longer raises an error for name-based interconnections if some systems have common input names and one of these inputs are to be kept. ** estim Add input/output/state names to the returned system. Support name-based selection of inputs (arguments 'sensors' and 'known'). ** sumblk Add signal names as input/output groups if argument n > 1. ** minreal If state-space models already have a minimal realization, then no state transformations are applied to the returned model. In other words, if the number of states cannot be reduced (with the chosen tolerance), the model is returned unchanged. Note that if the user sets the tolerance to the maximum value of 1, every state-space model will be reduced to zero states. There's nothing wrong with that, it's just how numerical computation works. =============================================================================== control-2.8.5 Release Date: 2015-10-01 Release Manager: Lukas Reichlin =============================================================================== ** nyquist, nichols Specifying a frequency range no longer errors out, i.e. nyquist (sys, {wmin, wmax}) ** pid, pidstd New functions for improved Matlab compatibility. ** ss Support ss (a, b, c, 0) for Matlab compatibility. (Thanks to Thomas Vasileiou) ** tf Fixed a problem which caused the expression below to fail. tf (Boeing707) \ tf (Boeing707) =============================================================================== control-2.8.4 Release Date: 2015-09-02 Release Manager: Lukas Reichlin =============================================================================== ** tf Fixed a bug which affected interconnections of MIMO transfer functions. (Reported by Piet Wertelaers) ** VLFamp Included new demo created by Thomas D. Dean. =============================================================================== control-2.8.3 Release Date: 2015-07-01 Release Manager: Lukas Reichlin =============================================================================== ** LTI models & iddata datasets Support partial matching of property names. ** mpower Fixed bug #45336. <http://savannah.gnu.org/bugs/?45336> Improved reliability for the power computation of MIMO transfer functions. (Reported by Nick Jankowski) ** set Fixed bug #45371. <http://savannah.gnu.org/bugs/?45371> The iddata properties 'name', 'notes' and 'userdata' are now stored as expected. (Thanks to Petr Ledvina) =============================================================================== control-2.8.2 Release Date: 2015-06-15 Release Manager: Lukas Reichlin =============================================================================== ** tf Fixed a problem when converting certain MIMO descriptor state-space systems to transfer function models. ** minreal Fixed bug #43263. <http://savannah.gnu.org/bugs/?43263> Affected were transfer function models. (Thanks to Endre Kozma) ** n4sid, moesp, moen4 Fixed bug #41716. <http://savannah.gnu.org/bugs/?41716> Display a meaningful error message when the iddata dataset contains not enough samples per experiment. (Reported by John W. Eaton) ** rlocus Fixed bug #44949. <http://savannah.gnu.org/bugs/?44949> Fixed a problem with discontinuous plots for systems like the one below. (Thanks to Doug Stewart) sys = tf ([1 0 0 0 0 0 1], [1 0 0 0 1 0 0 0 0 1]) rlocus (sys) =============================================================================== control-2.8.1 Release Date: 2015-05-03 Release Manager: Lukas Reichlin =============================================================================== ** tf -- Revamped the modifications of TB01ZD from control version 2.8.0. The function now uses LAPACK routines to find the maximum norm element. (Thanks to Thomas Vasileiou) -- Improved error handling when converting state-space models. =============================================================================== control-2.8.0 Release Date: 2015-03-22 Release Manager: Lukas Reichlin =============================================================================== ** zero Compatibility fix in the C++ oct-file to support the upcoming Octave 4.0. (Thanks to Andreas Weber) ** isminimumphase Reverted changes from control-2.6.6. According to the definition of Byrnes/Isidori, the function tests whether the system has asymptotically stable zero dynamics. The poles are not tested. Note that the definition from Wikipedia is mixed up. For details, see the help text of the function (help @lti/isminimumphase) and the papers referenced therein. (Thanks to Ulf Schaper) ** series Fixed a bug which gave unnecessary error messages when the function is called with 4 arguments. (Thanks to Ulf Schaper) ** tf Resolved issues in MIMO state-space to transfer function conversion by implementing a more robust algorithm in SLICOT routine TB01ZD. The same algorithm is used in Octave's krylov function. (Thanks to Thomas Vasileiou) ** It is now possible to cross-compile the control package. (Thanks to John Donoghue) ** Support for 64bit indexing, i.e. Octave versions built with the --enable-64 option. (Thanks to Mike Miller) ** The control package now depends on Octave version 3.8.0 or beyond. ** In order to comply with modified Octave Forge rules, the package no longer auto-loads by default. See "help pkg" for details on auto-loading. =============================================================================== control-2.6.6 Release Date: 2014-10-11 Release Manager: Lukas Reichlin =============================================================================== ** isminimumphase According to <http://en.wikipedia.org/wiki/Minimum_phase>, both the zeros and the poles of a minimum-phase system must be strictly inside the left complex half-plane (continuous-time case) or inside the unit circle (discrete-time case). Previously, the poles were not tested. (Thanks to Endre Kozma) =============================================================================== control-2.6.5 Release Date: 2014-06-16 Release Manager: Lukas Reichlin =============================================================================== ** LTI models -- The operator "times" (.*) no longer errors out when it is called with one SISO and one MIMO LTI system. The operator behaves now the same way as Octave's built-in "times" for one scalar and one matrix. -- The function "repmat" is now overloaded for LTI systems. -- Added function "repsys" as an alias for "repmat" for the sake of Matlab compatibility. ** zero Fix crash in case of empty state-space models, e.g. zero (ss) =============================================================================== control-2.6.4 Release Date: 2014-05-05 Release Manager: Lukas Reichlin =============================================================================== ** LTI models -- Fixed bug #42082. <https://savannah.gnu.org/bugs/?42082> The operators mtimes (*), mldivide (\) and mrdivide (/) no longer error out when they are called with one SISO and one MIMO LTI system. They now behave the same way as they do with one scalar and one matrix. -- Refuse struct arrays as input and output groups. -- Display non-empty properties of type 'name'. ** TF models -- Added TF-specific horzcat ([tf1, tf2]) and vertcat ([tf1; tf2]) operators which override the general LTI operators. Their introduction avoids the conversion to state-space and back when MIMO transfer functions are concatenated horizontally and/or vertically. -- Added operator times (.*) to compute Hadamard/Schur product of two transfer function matrices. This operator is useful to compute the Relative-Gain Array (RGA), e.g. G = tf (Boeing707) RGA = G .* inv (G).' RGA(0) =============================================================================== control-2.6.3 Release Date: 2014-04-22 Release Manager: Lukas Reichlin =============================================================================== ** SS models For interconnections, support special case where the internal matrix (I - D*M) is singular, e.g. feedback (ss (-1, 1, 4, 1), '+') ** FRD models Fixed bug which let frequency response plots fail, e.g. bode (frd (tf (1, [1, 1]))) ** tf Refuse denominators which are zero. ** c2d For zero-order hold approximation, use SLICOT MB05ND instead of Octave's "expm" to compute the matrix exponential. Better accuracy is to be expected. ** connect -- Improved argument checking for legacy connection matrix. -- Document usage of index-based interconnections. ** inv -- Handle i/o names and groups correctly. -- Conserve the meaning of states by using the Matlab-compatible formula instead of the SLICOT-compatible one. -- Always use conversion to state-space and back for the inversion of MIMO transfer functions, even for 2x2 systems. ** pole Compute poles of descriptor state-space models with SLICOT AG08BD instead of Octave's built-in "eig" function. ** zero The gain of descriptor state-space models is now computed correctly. (Special thanks to Thomas Vasileiou for all the fixes above) ** rlocus -- Function "rlocus" now supports the fltk graphics toolkit. (Thanks to Doug Stewart) -- Fixed bug #41820. <https://savannah.gnu.org/bugs/?41820> Function "rlocus" no longer errors out for certain systems like rlocus (tf ([1, 4, 4], [1, 8, 1, 8, 0])) ** transpose, ctranspose Delete i/o groups of transposed (sys.') or conjugate transposed (sys') LTI models. ** IDDATA identification datasets Raise an error if non-real-valued input or output matrices are assigned to time-domain datasets via the "set" function or subscripted assignment. =============================================================================== control-2.6.2 Release Date: 2014-02-02 Release Manager: Lukas Reichlin =============================================================================== ** hinfsyn, mixsyn By default, hinfsyn and mixsyn compute now an optimal instead of a suboptimal controller. Furthermore, Matlab compatibility is improved if hinfsyn/mixsyn is called with more than three/four input arguments. (Thanks to Thomas Vasileiou for the gamma iteration) The old behavior (sub-optimal controller) can be restored by the expressions hinfsyn (P, nmeas, ncont, 'method', 'sub') mixsyn (G, W1, W2, W3, 'method', 'sub') ** h2syn, hinfsyn, mixsyn, ncfsyn For Matlab compatibility, the third return argument is now norm "gamma". The info struct is now returned as fourth argument. [K, N, gamma, info] = *syn (G, …) ** mktito New function to partition plant for robust control. "mktito" is also used by function "augw". If a plant is partitioned that way, one can omit the inputs "nmeas" and "ncon" when calling the functions "hinfsyn" and "h2syn". ** ss The conversion of realizable descriptor systems to regular state-space form is now possible, even when the descriptor matrix "E" is singular. (Thanks to Thomas Vasileiou and Bruce Minaker) =============================================================================== control-2.6.1 Release Date: 2013-12-10 Release Manager: Lukas Reichlin =============================================================================== ** LTI models Raise an error if the user tries to create an ingroup or outgroup with indices larger than the number of inputs m or outputs p. ** thiran New function to approximate a continuous-time delay by a discrete-time allpass Thiran filter. (Thanks to Thomas Vasileiou and Spencer Jackson) ** end "end" indexing for LTI and IDDATA objects works now as expected. =============================================================================== control-2.6.0 Release Date: 2013-10-24 Release Manager: Lukas Reichlin =============================================================================== ** LTI models -- Support for name-based channel selection in various commands. Example: sys = Boeing707, sys('pitch', {'rudder', 'thrust'}) instead of sys(2, [2, 1]). -- New properties "ingroup" and "outgroup" to pool several channels: sys.ingroup.controls = [3, 1], sys.outgroup.measurements = [1, 2] sys('measurements', 'controls') instead of sys([1, 2], [3, 1]). -- Support names instead of indices in commands like "feedback" and "xperm". ** connect Support name-based interconnections. This means that the LTI models passed to "connect" will be interconnected automatically if they have their inputs and outputs named accordingly. ** sumblk New function to build summing junctions for name-based interconnections by "connect". Example: Sum = sumblk ('e = r - y + n') ** tf State-space to transfer function conversions of static gains, e.g. "tf (ss (5))", no longer error out. (Thanks to Thomas Vasileiou) ** IDDATA identification datasets Support for name-based output, input and experiment selection similar to LTI models. =============================================================================== control-2.4.5 Release Date: 2013-10-07 Release Manager: Lukas Reichlin =============================================================================== ** Compatibility to GNU Octave 3.8 Replaced line continuation marker "\" by "..." to avoid deprecated syntax warning. (Thanks to John W. Eaton) ** db2mag, mag2db New functions to convert Decibels to Magnitude and vice versa. ** d2d New function for resampling of discrete-time models. =============================================================================== control-2.4.4 Release Date: 2013-08-11 Release Manager: Lukas Reichlin =============================================================================== ** zero -- Fix documentation. Function "zero" computes the invariant zeros, not the transmission zeros when it is called with one input argument. -- Added new options to compute the system, transmission, input decoupling and output decoupling zeros besides the already existing invariant zeros. Examples: z = zero (sys, 'system'), z = zero (sys, 'transmission') -- Return an "info" struct as third output argument. It contains additional rank information as well as Kronecker indices and the numbers of infinite elementary divisors. Example: [z, k, info] = zero (sys) (Special thanks to Ferdinand Svaricek) ** resample The "resample" function for "iddata" identification datasets now handles unspecified sampling times (tsam = -1) correctly. ** Time response functions (impulse, initial, lsim, ramp, step) Fix a thinko introduced with control-2.4.3. In some cases, several responses were mistakingly plotted on the same subplot. (Thanks to Thomas Vasileiou) ** Various documentation enhancements and fixes. =============================================================================== control-2.4.3 Release Date: 2013-07-12 Release Manager: Lukas Reichlin =============================================================================== ** resample The resample function for iddata sets now adjusts the sampling time correctly after resampling. ** Time response functions (impulse, initial, lsim, ramp, step) Don't use subplot for SISO models. This allows the user to plot different responses on a single figure by calling subplot. (Thanks to Matthias Meier) ** h2syn, hinfsyn, mixsyn, ncfsyn Third return argument is now an info struct. [K, N, info] = *syn (G, …) ** optiPID Beef up documentation. =============================================================================== control-2.4.2 Release Date: 2013-02-16 Release Manager: Lukas Reichlin =============================================================================== ** Transfer function to state-space conversion (Thanks to Thomas Vasileiou): -- Fix crash. -- Fix bug if denominators are zero. ** minreal Fix crash in minreal for state-space systems. (Thanks to Thomas Vasileiou) ** sigma The plot types 1, 2, 3 were no longer supported since the introduction of multi-system plots in control-2.3.54. The help text is now updated accordingly and cruft is removed from the codebase. ** mixsyn, ncfsyn, Madievski Beef up help text. =============================================================================== control-2.4.1 Release Date: 2012-11-01 Release Manager: Lukas Reichlin =============================================================================== ** impulse, initial, lsim, step These time response functions now error out correctly when the user tries to plot multiple systems in one window with mismatching numbers of inputs and outputs. The problem was caused by Octave's built-in function "size_equal" which gave false positives for LTI objects. The problem is solved by overloading the built-in function with a new LTI method "size_equal". ** ramp Added a new time domain analysis function "ramp" which plots/computes the system's response to a ramp signal. ** c2d, d2c Added matched pole/zero discretization method "matched". Usage: Gd = c2d (Gc, Ts, 'matched'), Gc = d2c (Gd, 'matched') ** doc/control.pdf Revised PDF manual. There is now a function index at the end of the manual. Improved docstrings in several functions. =============================================================================== control-2.4.0 Release Date: 2012-09-26 Release Manager: Lukas Reichlin =============================================================================== ** Multiplot feature for time-domain plotting: impulse lsim initial step Supported are now function calls like impulse (sys1, sys2, ...), step (sys1, 'b', sys2, 'r', ...) lsim (sys1, '-k', sys2, '--k', u), initial (sys, sys2, x0) The multiplot feature for frequency-domain plotting has already been introduced with control-2.3.54. ** Anderson, Madievski, MDSSystem, optiPID Updated example scripts to use new multiplot feature. ** sensitivity Fixed a problem with plotting, introduced with control-2.3.54. ** doc/control.pdf Updated PDF manual. =============================================================================== control-2.3.54 Release Date: 2012-09-15 Release Manager: Lukas Reichlin =============================================================================== ** Multiplot feature for frequency-domain plotting: bode nichols pzmap bodemag nyquist sigma The functions above support calls like sigma (sys1, sys2, ...), nyquist (sys1, 'b', sys2, 'r', ...), bode (sys1, '-k', sys2, '-.k', sys3, ':k', {wmin, wmax}). Time domain functions are not yet multiplot ready, but they will follow in control-2.4.0. ** plot A selection of experiments from iddata identification datasets can be plotted by plot (dat, exp) instead of plot (dat(:,:,:,exp)). ** sensitivity Fixed a problem where an error was raised about an undefined function "issiso". ** All SLICOT function names have now leading and trailing underscores to emphasize their private nature. =============================================================================== control-2.3.53 Release Date: 2012-08-27 Release Manager: Lukas Reichlin =============================================================================== ** Added new functions for system identification, including: arx iddata ifft moen4 detrend nkshift moesp fft plot n4sid filter resample ** sensitivity Added new function to compute and plot the sensitivity margin Ms. ** feedback Fixed an argument check which caused false positive error messages. It was a copy-paste mistake affecting non-square systems. (Thanks to Tony Olivo) =============================================================================== 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. ===============================================================================

Package: control