Option set for
Create Default Option Set for State-Space Estimation Using Reduction of Regularized ARX Model
options = ssregestOptions;
Specify Options for State-Space Estimation Using Reduction of Regularized ARX Model
Create an option set for
ssregest that fixes the value of the initial states to
'zero'. Also, set the
opt = ssregestOptions('InitialState','zero','Display','on');
Alternatively, use dot notation to set the values of
opt = ssregestOptions; opt.InitialState = 'zero'; opt.Display = 'on';
Specify optional pairs of arguments as
the argument name and
Value is the corresponding value.
Name-value arguments must appear after other arguments, but the order of the
pairs does not matter.
Before R2021a, use commas to separate each name and value, and enclose
Name in quotes.
opt = ssregestOptions('InitialState','zero') fixes
the value of the initial states to zero.
ARXOrder — ARX model orders
'auto' (default) | matrix of nonnegative integers
ARX model orders, specified as a matrix of nonnegative integers
nb nk]. The
max(ARXOrder)+1 must be greater
than the desired state-space model order (number of states). If you
specify a value, it is recommended that you use a large value for
To learn more about ARX model orders, see
RegularizationKernel — Regularizing kernel
'TC' (default) |
Regularizing kernel used for regularized estimates of the underlying ARX model, specified as one of the following values:
'TC'— Tuned and correlated kernel
'SE'— Squared exponential kernel
'SS'— Stable spline kernel
'HF'— High frequency stable spline kernel
'DI'— Diagonal kernel
'DC'— Diagonal and correlated kernel
For more information, see .
Reduction — Options for model order reduction
Options for model order reduction, specified as a structure with the following fields:
State elimination method. Specifies how to eliminate the weakly coupled states (states with smallest Hankel singular values). Specified as one of the following values:
Discards the specified states and alters the remaining states to preserve the DC gain.
Discards the specified states without altering the remaining states. This method tends to product a better approximation in the frequency domain, but the DC gains are not guaranteed to match.
Absolute and relative error tolerance for stable/unstable decomposition. Positive scalar values. For an input model G with unstable poles, the reduction algorithm of
ssregestfirst extracts the stable dynamics by computing the stable/unstable decomposition G → GS + GU. The
RelToltolerances control the accuracy of this decomposition by ensuring that the frequency responses of G and GS + GU differ by no more than
RelTol*abs(G). Increasing these tolerances helps separate nearby stable and unstable modes at the expense of accuracy. See
stabsep(Control System Toolbox) for more information.
AbsTol = 0; RelTol = 1e-8
Offset for the stable/unstable boundary. Positive scalar value. In the stable/unstable decomposition, the stable term includes only poles satisfying
Re(s) < -Offset * max(1,|Im(s)|)(Continuous time)
|z| < 1 - Offset(Discrete time)
Increase the value of
Offsetto treat poles close to the stability boundary as unstable.
InputInterSample — Input-channel intersample behavior
Input-channel intersample behavior for transformations between discrete time and continuous time, specified as
The definitions of the three behavior values are as follows:
'zoh'— Zero-order hold maintains a piecewise-constant input signal between samples.
'foh'— First-order hold maintains a piecewise-linear input signal between samples.
'bl'— Band-limited behavior specifies that the continuous-time input signal has zero power above the Nyquist frequency.
iddata objects have a similar property,
data.InterSample, that contains the same behavior value options.
InputInterSample value is
the estimation data is in an
software uses the
data.InterSample value. When the estimation data
is instead contained in a timetable or a matrix pair, with the
option, the software uses
The software applies the same option value to all channels and all experiments.
options — Option set for
ssregestOptions options set
Estimation options for
ssregest, returned as an
ssregestoptions option set.
 T. Chen, H. Ohlsson, and L. Ljung. “On the Estimation of Transfer Functions, Regularizations and Gaussian Processes - Revisited”, Automatica, Volume 48, August 2012.
Version HistoryIntroduced in R2014a
InputInterSample option allows intersample behavior specification for continuous models estimated from timetables or matrices.
iddata objects contain an
InterSample property that
describes the behavior of the signal between sample points. The
InputInterSample option implements a version of that property in
ssregestOptions so that intersample behavior can be specified also when
estimation data is stored in timetables or matrices.
R2018a: Renaming of Estimation and Analysis Options
The names of some estimation and analysis options were changed in R2018a. Prior names still work. For details, see the R2018a release note Renaming of Estimation and Analysis Options.