# Glossary

- Convex
- See
**element**
- Cubature method
- A cubature method on an
**element** consists in a set of nodes
(generally called gauss points) and corresponding loads which
define a approximated integration method. In *GetFEM++* it is defined
on the **reference elements**.
- Degree of freedom
- The degrees of freedom for a finite element method is the coefficients
which multiply the shape functions in order to describe a
(scalar or vector) field. Generally, they are the unknowns of the
problem in general.
- Element
- An element is a small piece of a domain with a special shape (a segment,
a triangle, a quadrilateron, an tetrahedron, a hexahedron or a prism
for dimensions less or equal to three. A mesh is the union of
non intersecting elements.
- Finite element method (fem)
- A finite element method is defined on a real element. It consist on a
certain number of degrees of freedom linked to the corresponding shape
functions and a manner to glue the degrees of freedom from a element
to a neighbour element.
- Integration method
- See
**cubature method**.
- Quadrature method
- See
**cubature method**.
- Mesh
- The mesh is composed of
**elements**. in *GetFEM++*, these elements are
often called **convexes**. A mesh can be composed of elements of different
dimensions (triangles, segments, quadrilaters, tetrahedra,
hexahedra ...).
- Mesh_Fem
- The mesh_fem object is a mesh with a
**finite element method** defined
on each **element**. This
represent a finite element space on which a unknown or a data on the
considered domain will be discribed.
- Mesh_Im
- The mesh_im object is a mesh with a
**cubature method** defined on
each **element**. It is used in assembly procedures.
- Reference element
- A reference element or a convex of reference is a special
**element**
on which the elementary computations (integrals) are performed.
For instance, the reference segment in *GetFEM++* is the segment [0,1].
The reference triangle is the triangle (0,0), (0,1), (1,0). etc.