© 2004 by London Mathematical Society
Formulas for Liapunov Functions for Systems of Linear Difference Equations
Department of Mathematics, University of Tennessee at Chattanooga Chattanooga, TN 37403, USA. E-mail: john-graef{at}utc.edu
Department of Mathematics and Statistics, Mississippi State University Mississippi State, MS 39762, USA. E-mail: qian{at}math.msstate.edu
Department of Mathematics and Computer Science, Fayetteville State University Fayetteville, NC 28301, USA. E-mail: bzhang{at}uncfsu.edu
Received 17 June 2002.
Explicit quadratic Liapunov functions that provide necessary and sufficient conditions for the asymptotic stability of the system of linear difference equations x (t + 1) = Ax(t) are constructed by transforming the original systems to y (t + 1) = Gy(t), where G is a companion matrix associated with the characteristic polynomial of A. A necessary and sufficient condition for all roots of the characteristic polynomial to lie in the unit circle |z| < 1 on the complex plane is also derived. 2000 Mathematicals Subject Classification 39A11, 93D05.
Key Words: linear systems of difference equations Liapunov functions asymptotic stability quadratic functions