function []=hw5_2_16(A,B)
% find e-vals of block matrix of (optional inputs) A and B
% I have A and B as input just cause I wanted to play around with other matrices

% default values of A and B
if nargin<2
    A=[1,2,2; 5,6,-2; 1,-1,0];
    B=[2,0,1; 4,-5,1; 1,0,0];
end

% if other A and B are entered make sure it'll work
[n1,n2]=size(A);
[n3,n4]=size(B);
if ~(n1==n2)|~(n2==n3)|~(n3==n4)
    break
end

C=[A,B;B,A];
disp('e-vals of C (sorted)')
disp(sort(eig(C)))

disp('e-vals of A+B')
e1=eig(A+B);
disp(e1)
disp('e-vals of A-B')
e2=eig(A-B);
disp(e2)
disp('e-vals of A+B and A-B (sorted together)')
disp(sort([e1;e2]))