On improved delay-dependent stability criterion of certain neutral differential equations

In this letter, the problem for an asymptotic stability of the following neutral differential equation:ddt[x(t)+px(t-τ)]=-ax(t)+btanhx(t-σ)is considered. Based on the Lyapunov method, a stability criterion, which is delay-dependent on both τ and σ, is derived in terms of linear matrix inequality (LMI). Two numerical examples are included to show the effectiveness of the proposed method.