The variational approach, including the direct methods and finite elements, is one of the main tools of engineering analysis. However, it is difficult to appreciate not only for seniors but for graduate students too. It is possible to make this subject easier to understand with the help of symbolic manipulation codes (SMC). The easiness with which these codes provide analytical results allow for a student or researcher to focus on the ideas rather than on calculational difficulties. The very process of programming with SMC encourages appreciation of the qualitative aspects of investigations. Saving time and effort, they enable undergraduates to deal with the subjects generally regarded as graduate courses. There is a habitual aspect too. These days it is more convenient for a student (researcher) to work with a keyboard than with a pencil. Moreover, semantic features of the codes may allow for generalizations of the standard techniques, which would be impossible to achieve without the computer's help.

Technological developments in composite materials, non-destructive testing, and signal processing as well as biomedical applications, have stimulated wide-ranging engineering investigations of heterogeneous, anisotropic media and surface waves of different types. Wave propagation in solids is now of considerable importance in a variety of applications. The book presents many of the key results in this field and interprets them from a unified engineering viewpoint. The conceptual importance and relevance for applications were the prevailing criteria in selecting the topics. Included are body and surface waves in elastic, viscoelastic, and piezoelectric media and waveguides, with emphasis on the effects of inhomogeneity and anisotropy. The book differs in many aspects from the other monographs dealing with wave propagation in solids. It focuses on physically meaningful theoretical models, a broad spectrum of which is covered, and not on mathematical techniques. Some of the results, particularly those dealing with waves in composites, are given for the first time in the monographical literature. Both, exact and approximate approaches, are discussed. While the subject is advanced, the presentation is at an intermediate level of mathematical complexity, making understanding easier.