2 c diverses operations sur les entiers 1, 2, 3
3 c=======================================================================
4 c per1a3 : entier pour la permutation circulaire (1,2,3)
5 c per1a3(-1,i) = entier avant i
7 c per1a3( 1,i) = entier apres i
8 c per1a3( 2,i) = entier 2 places apres i = per1a3(-1,i)
9 c per1a3(-1,1) = 3, per1a3(-1,2) = 1, per1a3(-1,3) = 2
10 c per1a3( 0,1) = 1, per1a3( 0,2) = 2, per1a3( 0,3) = 3
11 c per1a3( 1,1) = 2, per1a3( 1,2) = 3, per1a3( 1,3) = 1
12 c per1a3( 2,1) = 3, per1a3( 2,2) = 1, per1a3( 2,3) = 2
13 c-----------------------------------------------------------------------
14 integer per1a3(-1:2,3)
15 common /ope1a3/ per1a3