Quadratic phase
= Quadratic phase
A quadratic phase on $\mathbb F_p^n$ is a function $x\mapsto e_p(q(x))$, where $q$ is a <quadratic form> and $e_p(t)=e^{2\pi it/p}$. Its third multiplicative derivative is one, so its $U^3$ norm is one.
= Quadratic phase
A quadratic phase on $\mathbb F_p^n$ is a function $x\mapsto e_p(q(x))$, where $q$ is a <quadratic form> and $e_p(t)=e^{2\pi it/p}$. Its third multiplicative derivative is one, so its $U^3$ norm is one.