I chose this font for the display versions of the text because it appears better on the screen than
does the more common Times font. The choice of available mathematics fonts is more limited.
I’d like to thank the students who found some, but probably not all, of the mistakes in the
text. Also Howard Gordon, who used it in his course and provided me with many suggestions for
improvements. Prof. Joseph Tenn of Sonoma State University has given me many very helpful ideas,
correcting mistakes, improving notation, and suggesting ways to help the students.
2008
A change in notation in this edition: For polar and cylindrical coordinate systems it is common to use
theta for the polar angle in one and phi for the polar angle in the other. I had tried to make them the
same (θ) to avoid confusion, but probably made it less rather than more helpful because it differed from
the spherical azimuthal coordinate. In this edition all three systems (plane polar, cylindrical, spherical)
use phi asφ= tan−^1 (y/x). In line integrals it is common to usedsfor an element of length, and
many authors will usedSfor an element of area. I have tried to avoid this confusion by sticking tod`
anddArespectively (with rare exceptions).
In many of the chapters there are “exercises” that precede the “problems.” These are supposed
to be simpler and mostly designed to establish some of the definitions that appeared in the text.
This text is now available in print from Dover Publishers. They have agreed that the electronic
version will remain available online.
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