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Estimate Transfer Function Models by Specifying Number of Poles

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This example shows how to identify a transfer function containing a specified number of poles for given data.

Load time-domain system response data and use it to estimate a transfer function for the system. 

load iddata1 z1;
np = 2;
sys = tfest(z1,np);

z1 is an iddata object that contains time-domain, input-output data.

np specifies the number of poles in the estimated transfer function.

sys is an idtf model containing the estimated transfer function.

To see the numerator and denominator coefficients of the resulting estimated model sys, enter: 

sys.Numerator;
sys.Denominator;

To view the uncertainty in the estimates of the numerator and denominator and other information, use tfdata.