The Action Principle and Partial Differential Equations pdf epub fb2

The Action Principle and Partial Differential Equations by Demetrios Christodoulou pdf epub fb2

The Action Principle and Partial Differential Equations Author: Demetrios Christodoulou
Title: The Action Principle and Partial Differential Equations
ISBN: 0691049572
ISBN13: 978-0691049571
Other Formats: doc lrf txt lit
Pages: 328 pages
Publisher: Princeton University Press (December 28, 1999)
Language: English
Category: Science & Math
Size PDF version: 1833 kb
Size EPUB version: 1755 kb
Subcategory: Mathematics




This book introduces new methods in the theory of partial differential equations derivable from a Lagrangian. These methods constitute, in part, an extension to partial differential equations of the methods of symplectic geometry and Hamilton-Jacobi theory for Lagrangian systems of ordinary differential equations. A distinguishing characteristic of this approach is that one considers, at once, entire families of solutions of the Euler-Lagrange equations, rather than restricting attention to single solutions at a time. The second part of the book develops a general theory of integral identities, the theory of "compatible currents," which extends the work of E. Noether. Finally, the third part introduces a new general definition of hyperbolicity, based on a quadratic form associated with the Lagrangian, which overcomes the obstacles arising from singularities of the characteristic variety that were encountered in previous approaches. On the basis of the new definition, the domain-of-dependence theorem and stability properties of solutions are derived. Applications to continuum mechanics are discussed throughout the book. The last chapter is devoted to the electrodynamics of nonlinear continuous media.