Excerpt from Asymptotic Methods for the Solution of Dispersive Hyberbolic Equations An important class of asymptotic methods is characterized by the fact that certain curves, often called rays, play a central role in the theory. The rays are of fundamental importance because all of the functions which make up the various terms of the expansion can be shown to satisfy ordinary differential equations along these curves. Thus, in a sense, the method is one which reduces partial differential equations to ordinary differential equations. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.