After partial differential equations (PDEs), physics and electrical engineering majors typically progress to complex analysis, which can be approached from both pure and applied perspectives. While there is no strict order for learning these subjects, key topics often studied alongside PDEs include ordinary differential equations, linear algebra, and vector calculus. Complex analysis is frequently integrated into engineering curricula as part of vector calculus, and its difficulty can vary based on the teaching approach. Students should choose between pure and applied complex analysis courses based on their academic goals and interests. Overall, a solid foundation in various mathematical disciplines is essential for advanced studies in physics and engineering.