Last updates: 7 December 2009

Find the Fourier series for the function $f:[0,2\pi ]\to \mathbb{R}$ given by $f\left(x\right)={x}^{2}$. |

[BG]
A. Braverman and
D. Gaitsgory,
* Crystals via the affine Grassmanian*,
Duke Math. J.
**107** no. 3, (2001), 561-575;
arXiv:math/9909077v2,
MR1828302 (2002e:20083)