# Analytic continuation

1. Feb 19, 2007

### touqra

What is analytic continuation? Seems to be used often in QFT.

2. Feb 19, 2007

### HallsofIvy

Actually, it more mathematics than physics- If a function is analytic on an open subset of the complex numbers, then there is a unique way to define it outside that set in such a way that it is analytic for all complex numbers.