Variational formulations of some variable delay differential systems. +CD

The main theme of this work is to introduce the general form and fundamental concepts in ordinary and partial delay-differential equations with variable delays and then to find the variational formulation of delay-differential equations with variable delays in both cases, ordinary and partial and to provide the rules of minimizing the obtained functional in the subject of calculus of variation. Finally, to minimize the variational formulation using the direct-Ritz method and finding the approximate solution of delay-differential equations with variable delays.