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showConfidence

Display confidence regions on response plots for identified models

    Description

    example

    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.

    Examples

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    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);

    Figure contains 2 axes objects. Axes object 1 with title From: u1 To: y1, ylabel Magnitude (dB) contains an object of type line. This object represents sys. Axes object 2 with ylabel Phase (deg) contains an object of type line. This object represents sys.

    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);

    Figure contains 2 axes objects. Axes object 1 with title From: u1 To: y1, ylabel Magnitude (dB) contains an object of type line. This object represents sys. Axes object 2 with ylabel Phase (deg) contains an object of type line. This object represents sys.

    This plot depicts the confidence region for 1 standard deviation.

    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);

    Figure contains 2 axes objects. Axes object 1 with title From: u1 To: y1, ylabel Magnitude (dB) contains an object of type line. This object represents sys. Axes object 2 with ylabel Phase (deg) contains an object of type line. This object represents sys.

    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 using 2 standard deviations.

    sd = 2;
    showConfidence(h,sd);

    Figure contains 2 axes objects. Axes object 1 with title From: u1 To: y1, ylabel Magnitude (dB) contains an object of type line. This object represents sys. Axes object 2 with ylabel Phase (deg) contains an object of type line. This object represents sys.

    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