Finding the matrix I generated two iterations back, while loop

I need my code to remember the matrix it generated two iterations back, and if this matrix is equal to the present one I want the code to break out of my while loop. This is a variation of the 'game of life' and the functions are written in swedish.

%%
 
C = [0 0 0; 1 1 1;0 0 0];
 
B = [zeros(1, N); C; zeros(1, N)];
A = [zeros(N+2, 1) B zeros(N+2, 1)];
D=zeros(N+2);
 
same=0;
k=0;
while same==0;
k=k+1;
for i=2:N+1;
    for j=2:N+1;
    D(i,j)=antalgrannarv2(A,i,j);
    end
end
for i=1:N+2;
    for j=1:N+2;
    D(i,j)=celldestiny(D,i,j);
    end
end
 
if A==D;
    same=1;
else
    same=0;
end
 
%here I would like the program to remember the second last matrix it generated and if 
%the present one is equal, break out of the loop. 

A=D;
 
find(0)
clf
plotroutine(A)
pause(0.2)
 
 
end

Answer 1

[Matt J]

One option is to maintain a list of the last two D's in a cell array:

C = [0 0 0; 1 1 1;0 0 0];
 
B = [zeros(1, N); C; zeros(1, N)];
A = [zeros(N+2, 1) B zeros(N+2, 1)];
D=zeros(N+2);
 
Dprevious={A,D};  %<----------------added

same=0;
k=0;
while same==0;
k=k+1;
for i=2:N+1;
    for j=2:N+1;
    D(i,j)=antalgrannarv2(A,i,j);
    end
end
for i=1:N+2;
    for j=1:N+2;
    D(i,j)=celldestiny(D,i,j);
    end
end
 
if isequal(D, Dprevious{1}); %<------------changed
    same=1;
else
    same=0;
    Dprevious={Dprevious{2}, D};  %<-------- added
end 

A=D;
 
end

[William Larsson]

Thank you very much, it worked.