GRANVILLE SEWELL, PHD, is Visiting Professor of Mathematics at Texas A&M University and Professor of Mathematics at the University of Texas at El Paso. He is the developer of PDE2D, a general-purpose partial differential equation solver. Dr. Sewell has written three books and published more than fifty articles on numerical methods and applications. His employment history includes time with IMSL, Inc., (now Visual Numerics) and the University of Texas System Center for High Performance Computing.