User`s guide

Using Pole-Zero Plots to Validate Models
In addition, y ou can display a confidence interval for each pole and zero on the
plot. The confidence interval corresponds to the range of pole or zero values
with a specific probability of being the actual pole or zero of the system . The
toolbox u ses the estimated uncertainty in the model parameters to calculate
confidence intervals and assumes the estimates have a Gaussian distribution.
For example, for a 95% confidenceinterval,theregionaroundthenominal
pole or zero value represents the range of values that have a 95% probability
of being the true system pole or zero value. You can specify the confidence
interval as a probability (between 0 and 1) or as the number of standard
deviations of a Gaussian distribution. For example, a probability of 0.99 (99%)
corresponds to 2.58 standard deviations.
The following table summarizes the Zeros and Poles plot settings.
Zeros and Poles Plot Settings
Action
Command
Display the confidence
interval.
• To display the dashed lines on either side
of the nominal pole and zero values, select
Options > Show confi dence intervals.
Select this option again to hide the confidence
intervals.
• To change the confidence value, select
Options > Set % confidence level,and
chooseavaluefromthelist.
• To enter your own confidence level, sele c t
Options > Set confidence level > Other.
Enter the value as a pro bability (between 0
and 1) or as the nu m b er of stan d ard de viation s
of a Gaussian distribution .
Show real and
imaginary axes.
Select Style > Re/Im-axes.Selectthisoption
againtohidetheaxes.
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