X = 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
Y = 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15
X ↔ Y

Ext-GCD(4, 15) :

i GCD Bezout AOdd : AEven :
A B ax ay bx by |A-B| A↔B Sx Sy ax
Sx'
ay
Sy'
A
A/2
ax
ax + Y
ay
ay + X
ax
ax/2
ay
ay/2
0 4 15 1 0 0 1
1 4 15 1 0 0 1 11 2 16 4 8 2
2 2 15 8 2 0 1 13 1 Even Even 4 1
3 1 15 4 1 0 1 14 1 4 2 4 2 7 Even Even 2 1
4 7 1 2 1 4 1 6 0 6 2 6 2 3 Even Even 3 1
5 3 1 3 1 4 1 2 0 7 2 7 2 1 22 6 11 3
6 1 1 11 3 4 1 0
7 1 1 4 1 11 3 0
(4)(4) - (1)(15) = 1