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Supported Data

System Identification Toolbox™ software supports estimation of linear models from both time- and frequency-domain data. For nonlinear models, this toolbox supports only time-domain data. For more information, see Supported Models for Time- and Frequency-Domain Data.

The data can have single or multiple inputs and outputs, and can be either real or complex.

Your time-domain data should be sampled at discrete and uniformly spaced time instants to obtain an input sequence


and a corresponding output sequence


u(t) and y(t) are the values of the input and output signals at time t, respectively.

This toolbox supports modeling both single- or multiple-channel input-output data or time-series data.

Supported DataDescription
Time-domain I/O dataOne or more input variables u(t) and one or more output variables y(t), sampled as a function of time. Time-domain data can be either real or complex.
Time-series dataContains one or more outputs y(t) and no measured input. Can be time-domain or frequency-domain data.
Frequency-domain dataFourier transform of the input and output time-domain signals. The data is the set of input and output signals in frequency domain; the frequency grid need not be uniform.
Frequency-response dataComplex frequency-response values for a linear system characterized by its transfer function G, measurable directly using a spectrum analyzer. Also called frequency function data. Represented by frd or idfrd objects. The data sample time may be zero or nonzero. The frequency vector need not be uniformly spaced.


If your data is complex valued, see Manipulating Complex-Valued Data for information about supported operations for complex data.