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Topic: ETFE function questions
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ms

Posts: 61
Registered: 11/6/06
ETFE function questions
Posted: Mar 21, 2011 12:16 PM
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I am trying to use the ETFE function, but was wondering if someone
could help explain what is happening when performing this function.

The original function is:

A = etfe(data,M,N), when data is a form of iddata, M is a smoothing
operation, and N is the number (128 default) equally
spaced frequencies between 0 (excluded) and pi.

By looking at A in the editor, I see this:

IDFRD model G.
Contains Frequency Response Data for 1 output and 1 input
at 128 frequency points, ranging from 2.4544 rad/s to 314.16 rad/s.


My question is, how does changing N affect the interpretation of
data. For example, when I plot a bode diagram using the data, I
clearly see as N increases, I have more data points on the x axis
(frequency). Also, when looking at the editor, the frequency ranges
changes too. Should the value used for N be a function of the length
of the "data" vector? Does it matter if the data vector is smaller or
larger than N?

Thanks!



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