# Orthogonality of Laguerre L

## Theorem

The following formula holds: $$\displaystyle\int_0^{\infty} e^{-x} L_n(x) L_m(x) \mathrm{d}x = \delta_{mn},$$ where $e^{-x}$ denotes the exponential, $L_n$ denotes Laguerre L, and $\delta$ denotes Kronecker delta.