Euler's criterion

(redirected from Euler quadratic residue theorem)

Euler's criterion

[′ȯi·lərz krī′tir·ē·ən]
(mathematics)
A criterion for the congruence x n a (mod m) to have a solution, namely that a φ/d≡1 (mod m), where φ = φ(m) is Euler's phi function evaluated at m, and d is the greatest common divisor of φ and n.