I suspect that you want something like this:
>> Y = [1,7;3,9;11,12;15,18;22,12;12,23;15,19;10,22;17,28;111,123]
Y =
1 7
3 9
11 12
15 18
22 12
12 23
15 19
10 22
17 28
111 123
>> z = [9,12,18,12,23,19,22,28,123]
z =
9 12 18 12 23 19 22 28 123
>> [~,idx] = ismember(z,Y(:,2));
>> out = Y(idx,:)
out =
3 9
22 12
15 18
22 12
12 23
15 19
10 22
17 28
111 123
Using a loop is unlikely to be a neat or efficient solution.
