User`s guide

8 Model Analysis
Type model.dA at the prompt to access the estimated standard deviations
of the
model.A estimated property, where model represents the name
of the model object, and
A represents any estimated model property. In
general, you prefi x the name of the estimated property with a
d to get the
standard deviation estimate for that property. For example, to get the
standard deviation value of the A polynomial in an estimated ARX model,
type
model.da.
Note State-space models, estim ated with free parameterization, do
not have well-defined standard deviations of the matrix elements. To
displaymatrixparameteruncertaintiesinthiscase,first transform the
model to a canonical parameterization by setting the
ss model property
to
model.ss = 'canon'. For more information about free and canonical
parameterizations, see “Identifying State-Space Models” on page 3-73.
• Simulated output values for linear models with standard deviations using
the
sim command.
Call the
sim comm an d with outpu t arguments, where the second output
argument is the estimated standard deviation of each output value.
For example, type
[ysim,ysimsd]=sim(model,data),whereysim is
the sim ulated output,
ysimsd contains the sta nd a rd de viation s on th e
simulated output, and
data is the simulation data.
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