This volume is a textbook for a year-long graduate level course in All
research universities have applied mathematics for scientists and
engineers. such a course, which could be taught in different
departments, such as mathematics, physics, or engineering. I volunteered
to teach this course when I realized that my own research students did
not learn much in this course at my university. Then I learned that the
available textbooks were too introduc- tory. While teaching this course
without an assigned text, I wrote up my lecture notes and gave them to
the students. This textbook is a result of that endeavor. When I took
this course many, many, years ago, the primary references were the two
volumes of P. M. Morse and H. Feshbach, Methods of Theoretical Physics
(McGraw-Hill, 1953). The present text returns the contents to a similar
level, although the syllabus is quite different than given in this
venerable pair of books.