English: Illustration of how the finite-difference time-domain method in computational electromagnetism discretizes the space, interleaving the fields components for higher precision. For a system with translation symmetry along an axis, the TE/TM problems can be decoupled and solved separately. a) is a two-dimensional case with the magnetic field along the axis (perpendicular to the screen); b) is likewise a case with the electric field along the axis. In a general case, the Yee grid on figure c) is used.