An extension of the argument principle and nyquist criterion to a class of systems with unbounded

Makan Fardad, Bassam Bamieh

Research output: Contribution to journalArticle

7 Scopus citations


The Nyquist stability criterion is generalized to systems where the open-loop system has infinite-dimensional input and output spaces and an unbounded infinitesimal generator. The infinitesimal generator is assumed to be a sectorial operator with trace-class resolvent. The main result is obtained through use of the perturbation determinant and an extension of the argument principle to infinitesimal generators with trace-class resolvents.

Original languageEnglish (US)
Pages (from-to)379-384
Number of pages6
JournalIEEE Transactions on Automatic Control
Issue number1
StatePublished - Jan 2008
Externally publishedYes



  • Argument principle
  • Infinite-dimensional system
  • Nyquist stability criterion
  • Perturbation determinant
  • Unbounded infinitesimal generator

ASJC Scopus subject areas

  • Computer Science Applications
  • Control and Systems Engineering
  • Electrical and Electronic Engineering

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