##
General information

The MESH class is dedicated to the handling of unstructured meshes. Class MESHING deriving from it supplies functions for creating meshes from scratch (c.f. MESHING).

##
Content of the connectivity array

Underlying the unstructured meshes is the notion of connectivity. This section only covers meshes made out of standard elements, the `MED_POLYGON`

and `MED_POLYHEDRA`

case being detailed in section Polyhedra and polygons .

Nodal connectivity storage scheme

In

MEDMEM, an unstructured mesh nodal connectivity is defined with these arrays:

- the type array, which contains the number of cells for each present type;
- the nodal connectivity array containing the connectivity of each cell, all cells being sorted by type;
- the connectivity index array, which indicates the beginning of each cell in the connectivity array.

The cell types are ordered by their number of nodes; MED_POLYGON and MED_POLYHEDRA is always the last type, if present.

As an example, let us consider a mesh made out of a linear triangle, two linear quadrangles and a quadratic triangle (c.f. figure fig_connectivity_example ).

Example for mesh connectivity

The number of types is : 3

The type array writes : *MED_TRIA3*, *MED_QUAD4*, *MED_TRIA6*