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Approximate data using stable rational function object

`fit = rationalfit(freq,data)`

`fit = rationalfit(freq,data,tol)`

`fit = rationalfit(___,Name,Value)`

`[fit,errdb] = rationalfit(...)`

`fit = rationalfit(s_obj,i,j...)`

fits a rational function object of the form`fit`

= rationalfit(`freq`

,`data`

)

$$\begin{array}{cc}F(s)={\displaystyle \sum _{k=1}^{n}\frac{{C}_{k}}{s-{A}_{k}}+D,}& s=j*2\pi f\end{array}$$

to the complex vector `data`

over the frequency values in the positive
vector `freq`

. The function returns a handle to the rational function object,
`h`

, with properties `A`

, `C`

,
`D`

, and `Delay`

.

fits a rational function object of the form `fit`

= rationalfit(___,`Name,Value`

)

$$F(s)=({\displaystyle \sum _{k=1}^{n}\frac{{{\displaystyle C}}_{k}}{s-{{\displaystyle A}}_{k}}}+D){{\displaystyle e}}^{-s.Delay},\text{\hspace{0.05em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}s=j*2\pi f$$

with additional options specified by one or more
`Name,Value`

pair arguments. These arguments offer finer control over the
performance and accuracy of the fitting algorithm.

To see how well the object fits the original data, use the `freqresp`

function to compute the frequency response of the object. Then, plot the original data and the
frequency response of the rational function object. For more information, see the `freqresp`

reference page or the examples in the next section.

Gustavsen.B and A.Semlyen, “Rational approximation of frequency domain responses by
vector fitting,” *IEEE Trans. Power Delivery*, Vol. 14, No. 3, pp.
1052–1061, July 1999.

Zeng.R and J. Sinsky, “Modified Rational Function Modeling Technique for High Speed
Circuits,” *IEEE MTT-S Int. Microwave Symp. Dig.*, San Francisco,
CA, June 11–16, 2006.

`freqresp`

| `rfmodel.rational`

| `s2tf`

| `timeresp`

| `writeva`