~ismember does not work on my matrix

A=[1 1 5 6;
   2 2 1 5;
   3 1 4 2;
   4 4 2 1;
   5 6 2 1;]

B=[1 1 1;  %remain
   1 4 2;
   1 5 6;
   2 1 5;
   4 2 1;
   4 2 2;  %remain
   6 2 1;
   6 3 1;] %remain

I would like the output, C to display

C=[1 1 1;
   4 2 2;
   6 3 1;]

I tried the following:

[idx1,idx2] = ismember(A(:,2:4),B,'rows');

However, when I used ~

[idx1,idx2] = ~ismember(A(:,2:4),B,'rows');

An error's returned.

May I know why is this so and any suggestions on how to get around this?

Answer 1

[Andrei Bobrov]

Try

C = setdiff(B,A(:,2:end),'rows')

or

C = B(~ismember(B,A(:,2:end),'rows'),:)

[RDG]

Both works! Thanks. Will understand it for myself.