finding mismatched elements ~ismember

 A = [1 2 3;2 3 4;3 4 5;4 5 6;5 6 7;6 7 8;7 8 9]
 B = [2 3 4;6 7 8]
 flag = ~ismember(A,B,'rows');
 index = find(flag);
 q = A(index(flag))

The error is

 ??? Index exceeds matrix dimensions.

and The index finds only first elements of each row. The remaining two should also find it.. So, how to do it.?

[Matt J]

The index finds only first elements of each row. The remaining two should also find it.

This is not clear. Write explicitly what you want "index" and "q" to be.

[Andrei Bobrov]

q = A(flag,:);

or

q = A(index,:);

Answer 1

[Matt J]

q = setdiff(A,B,'rows')

Answer 2

[Walter Roberson]

Are these integers or numbers with fractions? If they are numbers with fractions then you cannot use ismember() in most cases.

http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F