1 Introduction

This manual presents the Iterative Finite Element Matrix (IFEM) library, a library for easily solving matrix problems derived from finite-element formulations. The library is designed to be matrix-free, in that the only matrix operation required is matrix-vector product, and hence the entire matrix need never be assembled

IFEM is built on the mesh and communication capabilities of the Charm++ FEM Framework, so for details on the basic runtime, problem setup, and partitioning see the FEM Framework manual.

1.1 Terminology

A FEM program manipulates elements and nodes. An element is a portion of the problem domain, also known as a cell, and is typically some simple shape like a triangle, square, or hexagon in 2D; or tetrahedron or rectangular solid in 3D. A node is a point in the domain, and is often the vertex of several elements. Together, the elements and nodes form a mesh, which is the central data structure in the FEM framework. See the FEM manual for details.