This easily accessible text combines mathematical precision, technical detail, and sound pedagogy to give complete coverage of linear systems. Its parallel discussion of continuous-time and discrete-time systems reflects a modern approach to these topics while capitalizing on their conceptual similarities. Covers of state variables, paying particular attention to applications in control theory; sections on the Fast Fourier Transform and its applications, introducing readers to modern techniques; and discussions of correlation integrals and summations as well as two-sided transforms which lead to applications of systems with noise input.