[GAP Forum] Quadratic residue in finite field

[Bill Allombert]

On Tue, Feb 07, 2017 at 01:40:47PM +0530, Surinder Kaur wrote:
> How can one check whether an element in a finite field with p^m elements is
> a quadratic residue or not?

Just test whether
a^((p^m-1)/2) = 1

Cheers,
Bill.