Subtracting 2 matrices of different dimensions

a{1}=[1 3 4 5;
      3 3 4 5;
      5 5 4 5
      2 4 2 6;
      6 5 2 6
      7 2 3 1;]

[b,idx]=unique(a{1}(:,3:4),'rows','stable');
uniquematrix{1}=a{1}(idx,:)

1  3  4  5  %Content of uniquematrix{1}
2  4  2  6
7  2  3  1

After a{1}-uniquematrix{1}

3 3 4 5 %My desired output
5 5 4 5
6 5 2 6

Is there a function to directly perform a{1}-uniquematrix{1}?

Answer 1

[Azzi Abdelmalek]

a=[1 3 4 5;
  3 3 4 5;
  5 5 4 5
  2 4 2 6
  6 5 2 6
  7 2 3 1]
[b,idx]=unique(a(:,3:4),'rows','stable')
out=a(setdiff(1:size(a,1),idx),:)

Answer 2

[Azzi Abdelmalek]

a=[1 3 4 5;
   3 3 4 5;
   5 5 4 5
   2 4 2 6
   6 5 2 6
   7 2 3 1]
[b,idx]=unique(a(:,3:4),'rows','stable')
uniquematrix=a(idx,:)
n1=size(a,1)
n2=size(uniquematrix,1)
uniquematrix=[uniquematrix;zeros(n1-n2,size(a,2))]
out=a-uniquematrix