Rao:Neutrophil:Dmatrix

function A = Dmatrix(N) %Diffusion Matrix D = 1; A = zeros(N,N); A(1,1) = -2*D; A(1,2) = D; A(1,N) = D; A(N,N) = -2*D; A(N,N-1) = D; A(N,1) = D; for i=2:N-1 A(i,i) = -2*D; A(i,i+1) = D;  A(i,i-1) = D; end A = (N-1)*(N-1)*A; A = sparse(A);