mathematical engineering
An interdisciplinary field applying mathematics to engineering problems; often contrasted with pure mathematics or theoretical physics.
He is majoring in mathematical engineering at university.
Solve optimization problems using methods from mathematical engineering.
応用数学 is broader applied mathematics, while 数理工学 specifically focuses on engineering applications.
工学 is general engineering; 数理工学 emphasizes the mathematical and analytical side.
Compound of 数理 (mathematical principles) + 工学 (engineering). The exact historical derivation is uncertain, but the term is a modern academic designation.