When the Tyrian princess Dido landed on the North African shore of the
Mediterranean sea she was welcomed by a local chieftain. He offered her
all the land that she could enclose between the shoreline and a rope of
knotted cowhide. While the legend does not tell us, we may assume that
Princess Dido arrived at the correct solution by stretching the rope
into the shape of a circular arc and thereby maximized the area of the
land upon which she was to found Carthage. This story of the founding of
Carthage is apocryphal. Nonetheless it is probably the first account of
a problem of the kind that inspired an entire mathematical discipline,
the calculus of variations and its extensions such as the theory of
optimal control. This book is intended to present an introductory
treatment of the calculus of variations in Part I and of optimal control
theory in Part II. The discussion in Part I is restricted to the
simplest problem of the calculus of variations. The topic is entirely
classical; all of the basic theory had been developed before the turn of
the century. Consequently the material comes from many sources; however,
those most useful to me have been the books of Oskar Bolza and of George
M. Ewing. Part II is devoted to the elementary aspects of the modern
extension of the calculus of variations, the theory of optimal control
of dynamical systems.