The book deals with continuous piecewise linear differential systems in
the plane with three pieces separated by a pair of parallel straight
lines. Moreover, these differential systems are symmetric with respect
to the origin of coordinates. This class of systems driven by concrete
applications is of interest in engineering, in particular in control
theory and the design of electric circuits. By studying these particular
differential systems we will introduce the basic tools of the
qualitative theory of ordinary differential equations, which allow us to
describe the global dynamics of these systems including the infinity.
The behavior of their solutions, their parametric stability or
instability and their bifurcations are described. The book is very
appropriate for a first course in the qualitative theory of differential
equations or dynamical systems, mainly for engineers, mathematicians,
and physicists.