MATLAB: How to set less than equal condition for two different cells

cellcell array

y=length(find(le({x},{rs})));

x = {rand(3,1)} ;
rs = {rand(3,1)} ;
y=length(find(le(x{1},rs{1})));

coordinates = [X, Y];

No point in creating the coordinates cell array, the way you've done it as it'll be erased and replaced by the above.

Don't convert Rs to a char!

Rs is a double here:

Rs=x-(x^2-s)/(2*x);

Here you convert it to a char.

    Rs='erreur';

Use a different variable instead or set Rs to nan.