Variational Methods in Nuclear Reactor Physics

This book is devoted to an exposition of those mathematical methods of a variational origin which are useful in obtaining approximate solutions to problems in science and engineering. These variational methods, which exploit the stationarity properties of variational principles to derive approximations, are, in a certain sense, complementary to the mathematical subject of the calculus of variations, in which the objective is to ascertain the mathematical consequences of a given functional possessing stationary or extremum properties. The distinction between variational methods and the calculus of variations is thus primarily a matter of emphasis and objectives. The standard topics of the calculus of variations are not treated explicitly in this book; the calculus of variations has a long history and there exist many excellent books on the subject (e.g., see the literature [1-5]).