findopOptions
Option set for findop
Description
opt = findopOptions(
creates
a default option set for computing the operating point of a specified
nonlinear ARX or HammersteinWiener model. Use dot notation to modify
this option set for your specific application. Options that you do
not modify retain their default values.model
)
creates
an option set with options specified by one or more opt
= findopOptions(model
,Name,Value
)Name,Value
pair
arguments.
Examples
Create Default Option Set for Operating Point Search
Create a default option set for findop
using an idnlarx
model
opt = findopOptions(idnlarx);
Create and Modify Default Operating Point Search Options
Create a default option set for findop
using an idnlhw
model.
opt = findopOptions(idnlhw);
Use dot notation to specify a subspace GaussNewton least squares search with a maximum of 25 iterations.
opt.SearchMethod = 'gn';
opt.SearchOptions.MaxIterations = 25;
Specify Options for Operating Point Search
Create an option set for findop
using an idnlarx
model. Specify a steepest descent least squares search with default search options.
opt = findopOptions(idnlarx,'SearchMethod','grad');
Input Arguments
model
— Estimated nonlinear model
idnlarx
model  idnlhw
model
Estimated nonlinear model, specified as one of the following:
idnlarx
modelidnlhw
model
NameValue Arguments
Specify optional pairs of arguments as
Name1=Value1,...,NameN=ValueN
, where Name
is
the argument name and Value
is the corresponding value.
Namevalue 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.
Example: 'SearchMethod','grad'
specifies a
steepest descent least squares search method
SearchMethod
— Numerical search method used for iterative parameter estimation
'auto'
(default)  'gn'
 'gna'
 'lm'
 'grad'
 'lsqnonlin'
 'fmincon'
Numerical search method used for iterative parameter estimation, specified as the one of the values in the following table.
SearchMethod  Description 

'auto'  Automatic method selection A combination of the
line search algorithms, 
'gn'  Subspace GaussNewton leastsquares search Singular
values of the Jacobian matrix less than

'gna'  Adaptive subspace GaussNewton search Eigenvalues
less than 
'lm'  LevenbergMarquardt least squares search Each
parameter value is 
'grad'  Steepest descent leastsquares search 
'lsqnonlin'  Trustregionreflective algorithm of This algorithm requires Optimization Toolbox™ software. 
'fmincon'  Constrained nonlinear solvers You can use the
sequential quadratic programming (SQP) and trustregionreflective
algorithms of the

SearchOptions
— Option set for the search algorithm
search option set
Option set for the search algorithm, specified as the commaseparated
pair consisting of 'SearchOptions'
and a search
option set with fields that depend on the value of
SearchMethod
.
SearchOptions
Structure When SearchMethod
is Specified
as 'gn'
, 'gna'
, 'lm'
,
'grad'
, or 'auto'
Field Name  Description  Default  

Tolerance  Minimum percentage difference between the current value
of the loss function and its expected improvement after the next iteration,
specified as a positive scalar. When the percentage of expected improvement
is less than  0.01  
MaxIterations  Maximum number of iterations during lossfunction minimization, specified as a positive
integer. The iterations stop when Setting
Use
 20  
Advanced  Advanced search settings, specified as a structure with the following fields.

SearchOptions
Structure When SearchMethod
is Specified
as 'lsqnonlin'
Field Name  Description  Default 

FunctionTolerance  Termination tolerance on the loss function that the software minimizes to determine the estimated parameter values, specified as a positive scalar. The
value of  1e5 
StepTolerance  Termination tolerance on the estimated parameter values, specified as a positive scalar. The value of  1e6 
MaxIterations  Maximum number of iterations during lossfunction minimization, specified as a positive
integer. The iterations stop when The value of
 20 
SearchOptions
Structure When SearchMethod
is Specified
as 'fmincon'
Field Name  Description  Default 

Algorithm 
For more information about the algorithms, see Constrained Nonlinear Optimization Algorithms (Optimization Toolbox) and Choosing the Algorithm (Optimization Toolbox).  'sqp' 
FunctionTolerance  Termination tolerance on the loss function that the software minimizes to determine the estimated parameter values, specified as a positive scalar.  1e6 
StepTolerance  Termination tolerance on the estimated parameter values, specified as a positive scalar.  1e6 
MaxIterations  Maximum number of iterations during loss function minimization, specified as a positive
integer. The iterations stop when  100 
To specify field values in SearchOptions
, create a
default findopOptions
set and modify the fields using
dot notation. Any fields that you do not modify retain their default
values.
opt = findopOptions; opt.SearchOptions.MaxIterations = 15; opt.SearchOptions.Advanced.RelImprovement = 0.5;
Output Arguments
opt
— Option set for findop
command
findopOptions
object
Option set for findop
command, returned
as a findopOptions
object.
Version History
Introduced in R2015aR2018a: 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.
See Also
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