Compare two different set of matrix?

How to compare two different set of matrix like this

 a=[81       
   82
   93
  102
   57
   98];

 b=[81       
   20
   43];

now i want to compare this two matrix 'b' and 'a', if matrix 'b' is matched with 'a' than, it should not display that value which is matched, only it should display remaining value of 'b' matrix. The answer should be like this..

 c= [20
    43];

Answer 1

[Azzi Abdelmalek]

setdiff(b,a)