idPolynomial1D

Class representing single-variable polynomial nonlinear estimator for Hammerstein-Wiener models

Syntax

t=idPolynomial1D('Degree',n)
t=idPolynomial1D('Coefficients',C)
t=idPolynomial1D(n)


Description

idPolynomial1D is an object that stores the single-variable polynomial nonlinear estimator for Hammerstein-Wiener models.

You can use the constructor to create the nonlinearity object, as follows:

t=idPolynomial1D('Degree',n) creates a polynomial nonlinearity estimator object of nth degree.

t=idPolynomial1D('Coefficients',C) creates a polynomial nonlinearity estimator object with coefficients C.

t=idPolynomial1D(n) a polynomial nonlinearity estimator object of nth degree.

Use evaluate(p,x) to compute the value of the function defined by the idPolynomial1D object p at x.

idPolynomial1D Properties

After creating the object, you can use get or dot notation to access the object property values. For example:

% List all property values
get(p)
% Get value of Coefficients property
p.Coefficients

Property Name	Description
Degree	Positive integer specifies the degree of the polynomial Default=1. For example: idPolynomial1D('Degree',3)
Coefficients	1-by-(n+1) matrix containing the polynomial coefficients.
Free	Option to fix or free the values in the mapping object. When you set Free to false, the object does not update during estimation.

Examples

Use idPolynomial1D to specify the single-variable polynomial nonlinearity estimator in Hammerstein-Wiener models. For example:

m=nlhw(Data,Orders,idPolynomial1D('deg',3),[]);

where 'deg' is an abbreviation for the property 'Degree'.

Tips

Use idPolynomial1D to define a nonlinear function $$y=F(x)$$, where F is a single-variable polynomial function of x:

$$F(x)=c(1)x^n+c(2)x^{(n-1)}+\dots +c(n)x+c(n+1)$$

Version History

Introduced in R2007b

R2021b: Use of previous idnlarx and idnlhw mapping object names is not recommended.

Starting in R2021b, the mapping objects (also known as nonlinearities) used in the nonlinear components of the idnlarx and idnlhw objects have been renamed. The following table lists the name changes.

Pre-R2021b Name	R2021b Name
wavenet	idWaveletNetwork
sigmoidnet	idSigmoidNetwork
treepartition	idTreePartition
customnet	idCustomNetwork
saturation	idSaturation
deadzone	idDeadZone
pwlinear	idPiecewiseLinear
poly1d	idPolynomial1D
unitgain	idUnitGain
linear	idLinear
neuralnet	idFeedforwardNetwork

Scripts with the old names still run normally, although they will produce a warning. Consider using the new names for continuing compatibility with newly developed features and algorithms. There are no plans to exclude the use of these object names at this time.