Flann

Flann is both an English surname and an Irish masculine given name, but has also been used as a feminine given name.
It might refer to:

Flann Fína mac Ossu, another name for King Aldfrith of Northumbria
Flann mac Lonáin, Irish poet
Flann Sinna, also called Flann mac Maíl Sechnaill, High King of Ireland
Flann Mainistrech, Irish scholar
Flann O'Brien, a pen name used by Irish writer Brian O'Nolan

FLANN, an acronym for Fast Library for Approximate Nearest Neighbors, is a C++ library for approximate nearest neighbor search in high-dimensional spaces.