quality:corruption
Kloosterman sum

If χ {\displaystyle \chi } is a Dirichlet character mod q {\displaystyle q} and ζ = e 2 π i q {\displaystyle \zeta =e^{\frac {2\pi i}{q}}} the Kloosterman sum K (a, b, χ) {\displaystyle K(a,b,\chi)} is defined as

If b = 0 {\displaystyle b=0} it is a Gauss sum.