Heaviside's direct operational calculus

OPERATIONAL CALCULUS is a very powerful tool for solving the differential equations of engineering. This article discusses some of the basic principles of Heaviside's direct operational calculus and how they can be applied to the solution of engineering problems. No attempt will be made to prove the various expressions that are to be used or to cover completely all the points of interest. The necessary justifications can be derived from the material to be presented in subsequent articles of this series.