function A = laplacian2d_kron(k)
% LAPLACIAN2D_KRON : discrete Laplace operator in 2 dimensions
%
% A = laplacian2d_kron(k) returns a k^2-by-k^2 sparse matrix

B = laplacian1d_sparse(k);
I = speye(k);
A = kron(I,B) + kron(B,I);

