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Vector Fitting

VFIT2 contains version 2.1 of vectfit (routine: vectfit2.m). The examples show how to fit scalars, columns and entire matrices, and how to formulate the model in the form of state-space models and pole-residue models.

This package shows how to apply the new version of Vector Fitting (vectfit2.m) to the rational approximation of frequency responses (scalar or vector functions). Important features:

  • Choose between sparse or non-sparse computations
  • Choose between Normal Equations or QR decomposition.
  • Options for skipping pole identification or residue identification
  • Choose between returned model on the form of pole-residue terms or state-space model

The user’s guide and the examples explain how to

  • Apply VF to multi-terminal systems
  • Maximize computational speed
  • Specify initial poles and weighting



File Purpose
vectfit2.m Version 2.1 of vectfit
vectfit2_userguide.pdf A guide on how to use vectfit2.m and description of included examples
vectfit_paper.pdf IEEE paper describing the mathematics of Vector Fitting (vectfit2.m)
Relaxed_VF.pdf IEEE paper describing the improvements in vectfit2.m with respect to pole relocation capability.
ex1.m Fitting a vector of 1 rational functions (single element)
ex2.m Fitting a vector of 2 rational functions
ex3.m Fitting a single element (transformer modeling)
ex4a.m Fitting a single column (network equivalencing)
ex4b.m Columnwise fitting (network equivalencing)
ex4c.m Matrix fitting (network equivalencing)
ex4d.m Matrix fitting with passivity “precautions” (network equivalencing)
ex5.m Fitting a vector of 5 elements (transmission line modeling)
ex6.m Fitting a pure time delay
tri2full.m Auxiliary routine used in ex4c,m, ex4d.m.
ss2pr.m Auxiliary routine used in ex4c,m, ex4d.m.
****.txt Frequency responses used in examples.