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(11, 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
11
15
1
0
0
1
1
11
15
1
0
0
1
4
1
1
1
1
1
2
16
12
8
6
2
2
↔
11
8
6
1
0
9
1
Even
Even
4
3
3
1
↔
11
4
3
1
0
10
1
5
3
5
3
5
20
14
10
7
4
5
1
10
7
4
3
4
0
14
10
14
10
2
Even
Even
7
5
5
2
1
7
5
4
3
1
1
22
16
11
8
6
1
1
11
8
4
3
0
7
1
1
11
8
4
3
0
(11)(11) - (8)(15) = 1