What do you want to do with the values that lie outside those limits? If you want to cap them, then you could do:
>> x(x>10) = 10;
>> x(x<5) = 5;
and similar for y and z.
If "A" is the matrix and x is the first column, as you say, then this means something like:
>> A(A(:,1)>10,1) = 10;
etc.
