check two matrix if its same display the matched value

i'm checking this two matrix a,b if it's same element than display the matched value and again the matched value only should get deleted and than it that should display what are all the values din't matched with 'b'(it means after deleting the remaining matrix should display).

a=[1 2 3 4 5 6 7];
b=[3 1 2 4 9 8 4];

Note: i'm compering 'a' with 'b'.

answer should be

c=[9 8];

Answer 1

[Jan]

a = [1 2 3 4 5 6 7];
b = [3 1 2 4 9 8 4];

c = b(~ismember(b, a))

Answer 2

[Azzi Abdelmalek]

a=[1 2 3 4 5 6 7];
b=[3 1 2 4 9 8 4]
out=setdiff(b,a,'stable')

[Matlab111]

i'm getting error

??? Error using ==> setdiff at 140 Unknown flag.

[Azzi Abdelmalek]

Try this

a=[1 2 3 4 5 6 7];
b=[3 1 2 4 9 8 4]
[ii,jj]=setdiff(b,a)
[~,idx]=sort(jj)
out=ii(idx)

[Matlab111]

ya i'm getting thank you