Joel Hass received his PhD from the University of California, Berkeley. He is currently a Professor of Mathematics at the University of California Davis. He has co-authored widely used calculus texts as well as calculus study guides. Hass’s current areas of research include the geometry of proteins, three-dimensional manifolds, applied maths, and computational complexity. Christopher Heil received his PhD from the University of Maryland. He is currently a Professor of Mathematics at the Georgia Institute of Technology. He is the author of a graduate text on analysis and a number of highly cited research survey articles. Heil's current areas of research include redundant representations, operator theory, and applied harmonic analysis. Maurice D. Weir (late) of the the Naval Postgraduate School in Monterey, California, was Professor Emeritus as a member of the Department of Applied Mathematics. He held a DA and MS from Carnegie-Mellon University and received his BS at Whitman College. He co-authored eight books, including University Calculus and Thomas’ Calculus.