Lars Edvard Phragmén

Lars Edvard Phragmén was a Swedish mathematician and engineer noted for his work in complex analysis and mathematical physics. He is particularly known for developing the Phragmén–Lindelöf principle, which is a theorem in complex analysis that provides conditions under which a holomorphic function can be extended to the boundary of a domain. This principle has important implications in various areas of mathematics, including potential theory and boundary value problems.