Fatou's theorem

Fatou's theorem addresses the behavior of certain mathematical functions called harmonic functions, which have applications in physics and engineering. It states that for a harmonic function defined inside a circle, the limit of the function's values as you approach the boundary (edge) of the circle exists almost everywhere when approaching along radii. In simple terms, as you get closer to the boundary from inside, the function’s values tend to stabilize or approach a specific value at most points, allowing us to understand boundary behavior of these functions in a precise way.