(I don't post often in that board).

So, I have two lists of same length L, the X list and the Y list.
And so basically, I'd like that if (X(n),Y(n))=(X(m),Y(m)), a calculus on the list returns 0, and that if there are no (n,m) so that (X(n),Y(n))=(X(m),Y(m)), the calculus returns non-zero.

For example,
X={1,4,3,6,7}
Y={2,4,5,2,1}
returns 0.

But
X={1,4,3,1,7}
Y={2,4,5,2,1}
returns non-zero.

I thought about putting the lists in a matrix and using det (and the 0/non-zero would be swapped but anyway) but the problem is that
1,2
1,2
returns the same as
1,2
2,4

So do you have any ideas ?

sum(not(abs(LX-LY

It doesn't work (both examples return 1) and it doesn't surprise me : doing LX-LY (and adding some commands after) would check if there is an equality X(n)=Y(n), but not (X(n),Y(n))=(X(m),Y(m)).

The best I can think of right now is:
DelVar ZFor(I,1,dim(LX
For(J,1,I)
If (LX(J)=LX(I)) and (LY(I)=LY(J
1->Z
End
End

Well yeah, I know that this would work, but I was wondering if there was not a fast method.

Oh, I didn't know that SortA could have several arguments !
Thanks, indeed I think that "something like this" should work (if not your code, something similar).

Yeah, I can do that or use two temporary lists that I don't care if they get swapped (but that method would use more RAM).
Anyway, thanks, your code seem to work perfectly.