Superconvergence for L2-projection in finite elements

Two classes of superconvergence points forL ²-projection u_n inn-degree finite elements on uniform grids are shown by element analysis method. Superconvergence points ofu _n aren + 1 order Gauss point G_n+1 for oddd≳-1 (so the endpoint of each element is of superconvergent), andn + 1 order pointset Z_n+1 for even n≥2 (which includes the endpoints and midpoint), respectively. Symmetry point is only an important part of them.