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showConfidence

Display confidence regions on response plots for identified models

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    Syntax

    showConfidence(plotHandle)
    showConfidence(plotHandle,stdDev)

    Description

    showConfidence(plotHandle) displays the confidence region on the response plot for an identified model using a default standard deviation of 1.

    example

    showConfidence(plotHandle,stdDev) displays the confidence region for sd standard deviations.

    example

    Examples

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    Open Live Script

    Show the confidence bounds on the bode plot of an identified ARX model.

    Obtain identified model and plot its bode response. 

    load iddata1 z1
sys = arx(z1, [2 2 1]);
h = bodeplot(sys);

    MATLAB figure

    z1 is an iddata object that contains time domain system response data. sys is an idpoly model containing the identified polynomial model. h is the plot handle for the bode response plot of sys.

    Show the confidence bounds for sys. 

    showConfidence(h);

    MATLAB figure

    This plot depicts the confidence region for 1 standard deviation.

    Open Live Script

    Show the confidence bounds on the bode plot of an identified ARX model.

    Obtain identified model and plot its bode response. 

    load iddata1 z1
sys = arx(z1, [2 2 1]);
bp = bodeplot(sys);

    MATLAB figure

    z1 is an iddata object that contains time domain system response data. sys is an idpoly model containing the identified polynomial model. bp is the chart object for the bode response plot of sys.

    Show the confidence bounds for sys using 2 standard deviations. 

    sd = 2;
showConfidence(bp,sd);

    MATLAB figure

    sd specifies the number of standard deviations for the confidence region displayed on the plot.

    Input Arguments

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    Plot handle for a response plot of an identified model, specified as a handle object. To obtain the plot handle, use the bodeplot, stepplot, impulseplot, nyquistplot, or iopzplot function.

    Standard deviation of confidence region, specified as a positive scalar. A common choice is three standard deviations, which gives 99.7% significance.

    Alternatives

    You can interactively enable the confidence region display on a response plot. Right-click the response plot, and select Characteristics > Confidence Region.

    Version History

    Introduced in R2012a

    See Also

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