A. Alsmadi et Dm. Wilkes, SIMPLIFYING AND EXTENDING A USEFUL CLASS OF SIGNALS AND IMPULSE RESPONSES, IEEE transactions on education, 38(4), 1995, pp. 301-305
Mathematics is an essential tool for studying science and engineering,
and calculus is one of the most important branches of mathematics for
engineering. In this paper a new formula for evaluating integral x(n)
e(ax) dx and a more generally applicable extension to polynomials are
developed. This new approach illustrates the intimate relationship be
tween differentiation and integration, and is simple enough for a fres
hman taking the first course in calculus to derive it. Although a clos
ed-form expression for this integral exists, it is cumbersome and rela
tively more difficult to remember than the forms proposed in the paper
. Also, the proposed formula readily generalizes to a larger class of
polynomials, thus becoming much more useful. We show that these formul
ae are particularly important for the analysis and use of a broad clas
s of signals commonly encountered in the classroom and in practical si
tuations. The proposed formulae are applied to Fourier Series, Fourier
Transforms, LaPlace Transforms, and time domain convolution.