rationalfit

Perform rationalfit on an S-parameters object

Syntax

[fit,errdb] = rationalfit(s,i,j)

[fit,errdb] = rationalfit(s)

Description

[fit,errdb] = rationalfit(s,i,j) uses the rationalfit function to construct a fit, an rfmodel.rational object fitting only the (i,j)th element of the S-parameter object s. This syntax is equivalent to rationalfit(s.Frequencies,rfparam(s,i,j),...).

[fit,errdb] = rationalfit(s) uses the rationalfit function to construct a fit, an N-by-N of rfmodel.rational objects (sharing identical poles) fitting all the N-by-N elements of the S-parameter object s. You can directly pass this N-by-N fit to freqresp, ispassive, passivity functions. This syntax is equivalent to rationalfit(s.Frequencies,s.Parameters).

Examples

Rationalfit of S-parameters

Read a file named passive.s2p and fit the 2-by-2 S-parameters.

S = sparameters('passive.s2p');
[fit,errdb] = rationalfit(S)

fit = 
  2x2 rfmodel.rational array with properties:

    A
    C
    D
    Delay
    Name

errdb = -40.4702

Input Arguments

s — S-parameter object

network parameter object

S-parameters, specified as an RF Toolbox™ network parameter object. To create this type of object, use the sparameters function.

i — Row index

positive integer

Row index of data to plot, specified as a positive integer.

j — Column index

positive integer

Column index of data to plot, specified as a positive integer.

Output Arguments

fit — Rational function object

rfmodel.rational object

One or more rational function objects, returned as an N-by-N rfmodel.rational object. The number of dimensions in data determines the dimensionality of h.

errdb — Relative error

-40 (default) | double

Relative error achieved, returned as a double, in dB.

Version History

Introduced before R2006a