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Analyze Data

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

Functions

bode Bode plot of frequency response, magnitude and phase of frequency response
bodemag Bode magnitude response of LTI models
plot Plot input-output data
advice Analysis and recommendations for data or estimated linear models
delayest Estimate time delay (dead time) from data
isreal Determine whether model parameters or data values are real
realdata Determine whether iddata is based on real-valued signals
feedback Identify possible feedback data
pexcit Level of excitation of input signals
impulseest Nonparameteric impulse response estimation
etfe Estimate empirical transfer functions and periodograms
spa Estimate frequency response with fixed frequency resolution using spectral analysis
spafdr Estimate frequency response and spectrum using spectral analysis with frequency-dependent resolution
iddataPlotOptions Option 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.

Working with Plots

How to plot data and models, identify data and models on a plot, select to plot specific input and output channels, set plot options, and print plots.

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