How can I assign a single value (index) for each point in a square?

I have a geometrical square with MxN dimensions and I need to assign for each pairs of points (x,y) a single index or value.

I've tried doing Index=mY+X but when X is too large index starts to repeat and there are no more single.

i.e m=2; Index=6=2*2+2 and also Index=6 when Index=2*1+4.

I need that every index be unique for each pair of x,y

Cheers!

Answer 1

[Oleg Komarov]

You can use sub2ind()

sub2ind([M,N], x,y)

[Matt Fig]

If OP is talking about a patch on R^2, then it cannot be done. If there is a certain spacing involved, such that for any successive pair (x1,y1) & (x2,y2), x2 = x1 + c or y2 = y1 + d or both, then something like SUB2IND will work.

[Gabriel González]

Genius! ajaj thanks!