"Version: 20171001"--Title page verso."A Morgan & Claypool publication as part of IOP Concise Physics"--Title page verso.Includes bibliographical references.1. Partial differential equations -- 2. Separation of variables -- 2.1. Helmholtz equation -- 2.2. Helmholtz equation in rectangular coordinates -- 2.3. Helmholtz equation in cylindrical coordinates -- 2.4. Helmholtz equation in spherical c…