This book introduces new methods in the theory of partial differential equations derivable from a Lagrangian. These methods constitute, in part, an extension to

This book introduces new methods in the theory of partial differential equations derivable from a Lagrangian. These methods constitute, in part, an extension to

The book is intended as an advanced undergraduate or first-year graduate course for students from various disciplines, including applied mathematics, physics an

Our understanding of the fundamental processes of the natural world is based to a large extent on partial differential equations (PDEs). The second edition of P

This volume is based on PDE courses given by the authors at the Courant Institute and at the University of Notre Dame, Indiana. Presented are basic methods for