<P>This third edition of a bestseller is now presented as a three-volume set, making it much more accessible and easier to use when searching for information. Maintaining the format that made its predecessors so popular, this edition has been extensively expanded, revised, and updated. It now contains nearly 12,000 entries. Each article provides definitions, formulas, illustrations, web links, bibliographic information, and facts from mathematics, the sciences, and engineering. Written by a single author, the encyclopedia is written in an informal style, making it accessible to anyone who has an interest in mathematics. The three-volume set is beautifully bound with much improved typesetting and format. </P><P><STRONG>Dramatically Expanded to Be the Most Comprehensive Library Reference on Mathematics Available Today</STRONG></P><UL><LI>Provides a versatile resource for students, faculty, and professionals working in mathematics, the sciences, and engineering</LI><LI>4300 pages with 4500 figures</LI><LI>Over 1000 pages of entirely new material</LI><LI>Nearly 12,000 entries now in 3 volumes</LI><LI>Updated for use with Mathematica<SUP>® </SUP>6 and 7</LI><LI>Entries contain definitions, formulas, illustrations, web links, bibliographic information, and useful facts </LI><UL><UL></UL></UL><LI>Content drawn from the widely respected and continuously updated http://mathworld.wolfram.com/</LI></UL><P> <STRONG>Improvements to the Third Edition include:</STRONG></P><P></P><UL><P><LI>Now more than 11,900 individual entries--4300 of them new (60% more than the previous edition)</LI><LI>Entries extensively revised, extended, and updated</LI><LI>Written in clear, precise, readable language that is accessible to students, scientists, engineers, and laypeople, while still retaining the rigor demanded by the mathematics professional</LI><LI>Extensive additions and updates in graph theory, discrete mathematics, number theory, plane geometry, special function theory, integer sequences, and the theory of mathematical constants</LI><LI>Updated with new research, computational, and theoretical results</LI><LI>3 handsomely bound volumes containing a total of 4300 pages--a full 1000 pages of content more than the previous edition</LI><LI>Printed on high-quality paper for durability and ease of reading</LI><LI>Completely new typesetting done by the author including higher quality formatting and tighter pagination</LI><LI>High-quality table layout and formatting</LI><LI>Now more than 1100 tables enumerating properties--three times as many tables as before</LI><LI>High-resolution line and grayscale figures and diagrams</LI><LI>Extensively illustrated with more than 4500 figures--nearly 3 times as many as before</LI><LI>Many figures updated and refined</LI><LI>Many new literature and internet citations</LI><LI>Updated with nearly 37,000 citations, many of them to recent literature--nearly 3 times as the previous edition</LI><LI>Nearly 5000 internet citations--10 times as many as before</LI><LI>Thousands of additional cross-references</LI><LI>Content updated for <EM>Mathematica</EM> 6 and 7</LI><LI><EM>Mathematica</EM> notebooks available for download on http://mathworld.wolfram.com/ for nearly 5000 of the entries</LI></UL><P><STRONG>Eric W. Weisstein</STRONG> began compiling scientific encyclopedias as a high school student more than 20 years ago. He studied physics and astronomy at Cornell University and California Institute of Technology and received his Ph.D. from Cal Tech in 1996. An expert Mathematica user since the 1990s, Weisstein continues to work closely with the main development teams at Wolfram Research, providing input and advice for future features of Mathematica. He is a sought-after speaker on mathematics communication, scientific computing, and knowledge management on the internet. He has participated in a number of important standards initiatives and led Wolfram Research’s contribution on a National Science Digital Library project. We