how to swap this matrix

i have this column of matrix

Z= 2

   4

   1

   7

   9
how to swap this 1 and 2

Answer 1

[Andrei Bobrov]

Z([1,2]) = Z([2,1]);

ADD

Z = [2
   4
   2
   1
   7
   9
   1
   1]; % new case

a = [1, 2]; % replacement value
[l,ii] = ismember(Z,a);
Z(l) = a(3-ii(l));

[Anusha]

how to swap 1st and 3rd position

[Andrei Bobrov]

Z([1,3]) = Z([3,1]);

Answer 2

[dpb]

Z(1:3)=flipud(Z(1:3));

Only works because of odd number, of course. In general to swap individual elements will still take the temporary to hold the one element while overwrite the other.