Two families of mixed finite elements for second order elliptic problems (Q1080633)

Two families of mixed finite elements are introduced in order to deal with second order elliptic problems. The asymptotic errors are the same as in the usual Raviart-Thomas-Nedelec spaces, but the new spaces have substantially smaller dimension; this fact should imply a greater computational efficiency, because the discretizations with the new spaces lead to algebraic systems of smaller order.