The Relative Approximation Error Fitting Criterion of Model Reduction

This paper presents the concept of relative approximation error, etc.analyzes some existent reduction methods, affirms the advantages of treating resonant peak system with FF-Padé method, etc. and points out their restrictions on treating good damping system.Thus, for good darning system, the relative approximation error criterion should be used to determine whether it is fitting or not and to select the reasonable point of fitting in times of need.