Our editorial board recently added Complex Analysis: An Open Source Textbook by Russell Howell and John Matthews to our list of approved texts. Suitable for use in a standard undergraduate complex analysis course, this book, originally published by Jones and Bartlett, is now freely available in accessible HTML and PDF. A low-cost print edition is coming in the summer of 2025.

Notable for its clarity, the exposition blends convincing motivation and careful explanations to help the reader develop a deep understanding of the subject. The complex numbers are introduced with a compelling historical treatment before complex functions, differentiability, and contour integration come into focus. Later chapters explore residue calculus, conformal mappings, and Fourier and Laplace transforms. Meaningful applications, such as steady-state temperature distributions, electrostatics, and two-dimensional fluid flow, are also included.

Each section concludes with an appropriate set of exercises, some of which include solutions. A forthcoming section on the book’s home page will include ideas for student projects suitable for including in a course or as part of an REU.