Fonctions mathématiques 1 Calcul du PGCD

u v u v
v= 0 v u
r←u mod v u ←v v ←r
v
u v pgcd(u, v) = 2pgcd(u/2, v/2)
u v pgcd(u, v) = pgcd(u/2, v)
pgcd(u, v) = pgcd(u−v, v)
u v u −v|u−v|< max(u, v)
k←0k←k+ 1 u←u/2v←v/2
u v
u v 2k
u t ← −v t ←u
t t ←t/2
t
t > 0u←t v ← −t|u| |u|
|t|
t←u−v t 6= 0 u·2k

1/d d > 1