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Analyze Data

Determine data characteristics such as delay, feedback, and excitation level

Functions

bodeBode plot of frequency response, or magnitude and phase data
bodemagBode magnitude response of LTI models
plotPlot input-output data
adviceAnalysis and recommendations for data or estimated linear models
delayestEstimate time delay (dead time) from data
isrealDetermine whether model parameters or data values are real
realdataDetermine whether iddata is based on real-valued signals
feedbackIdentify possible feedback data
pexcitLevel of excitation of input signals
impulseestNonparameteric impulse response estimation
etfeEstimate empirical transfer functions and periodograms
spaEstimate frequency response with fixed frequency resolution using spectral analysis
spafdrEstimate frequency response and spectrum using spectral analysis with frequency-dependent resolution
iddataPlotOptionsOption set for iddata/plot

Examples and How To

How to Plot Data in the App

After importing data into the System Identification app, as described in Represent Data, you can plot the data.

How to Plot Data at the Command Line

The following table summarizes the commands available for plotting time-domain, frequency-domain, and frequency-response data.

How to Analyze Data Using the advice Command

You can use the advice command to analyze time- or frequency- domain data before estimating a model.

Identify Delay Using Transient-Response Plots

You can use transient-response plots to estimate the input delay, or dead time, of linear systems.

Concepts

Is Your Data Ready for Modeling?

Before you start estimating models from data, you should check your data for the presence of any undesirable characteristics.

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