  Stability is a very important property of any physical system. By a stable
system, we broadly mean that small disturbances either in the system inputs or
in the initial conditions do not lead to large changes in the overall behavior
of the system. To be of practical use, a system must have to be stable. The
theory of stability is a vast, rapidly growing subject with prolific and
innovative contributions from numerous researchers. As such, an introductory
book that covers the basic concepts and minute details about this theory is
essential. The primary aim of this book is to make the readers familiar with
the various terminologies and methods related to the stability analysis of
time-invariant (autonomous) and time-varying (non-autonomous) systems. A
special treatment is given to the celebrated Liapunov's direct method which is
so far the most widely used and perhaps the best method for determining the
stability nature of both autonomous as well as non-autonomous systems. After
discussing autonomous systems to a considerable extent, the book concentrates
on the non-autonomous systems. From stability point of view, these systems are
often quite difficult to manage. Also, unlike their autonomous counterparts,
the non-autonomous systems often behave in peculiar manners which can make the
analysts arrive at misleading conclusions. Due to these issues, this book
attempts to present a careful and systematic study about the stability
properties of non-autonomous systems.
