A = [1 2 3 4 5; 6 7 8 9 0];
b = [1;2];
x = lsqminnorm(A,b).'
norm(x)
norm(A*x.'-b)
if you search for the solution for which x has minimum norm.
If you only search for an arbitrary least-squares solution (i.e. for an x for which norm(e2) is minimum), simply use
x = (A\b).'
norm(x)
norm(A*x.'-b)
