>> a = []
a =
[]
>> a = [a;1,2]
a =
1 2
>> a = [a;1,2]
a =
1 2
1 2
>> a = [a;5,6]
a =
1 2
1 2
5 6
>> a=[a;5,5]
a =
1 2
1 2
5 6
5 5
>> a(4)-a(2)
ans =
4
