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Preprocessor ** IMAGXX** lists the contents of an arbitrary type D.S. It calls module IM* DS*
corresponding to the D.S. under consideration (see [MODULEF User Guide - 2]).

Preprocessor ** INFOXX** obtains, in particular, information about a mesh stored in a
D.S. ** NOPO** or ** GEOM**.
In the case of a ** NOPO** type D.S., it calls module INFONO, described in chapter 4 of
[MODULEF User Guide - 3].
In the case of a ** GEOM** type D.S., it calls module INFOGE, described in the same chapter of
[MODULEF User Guide - 3].

The information obtained is the following, depending on the options chosen:

- nothing,
- call IMNOPO,
- verification of the elements in the mesh (test of surfaces and volumes),
- output array NOP2,
- output the element with given number,
- output the elements containing a point with given number,
- output the elements containing a point with coordinates given,
- output the elements containing a node with given number,
- output the list of points with a given reference,
- output the list of nodes with a given reference,
- output the elements containing an edge with given reference,
- output the elements containing an edge or face with given reference,
- output the elements with sub-domain number given,
- output the coordinates of a point with a given number,
- output the elements containing a face with a given reference,

- nothing,
- call IMGEOM,
- output array GEO2,
- output the list of points with a given reference,
- output the elements with a given sub-domain number,
- output the coordinates of a point with given number,

When changing (using ** NOPGXX** or ** GEONXX**) from one type of D.S. to another, we can obtain
one or the other type of information.

Preprocessor ** REFPXX** calls module REFPOI (see [MODULEF User Guide - 3]) which lists the numbers of the points in a
mesh with a given reference.

Preprocessor ** REFNXX** calls module REFNOP (see [MODULEF User Guide - 3]) which lists the numbers of the elements
in a mesh containing a face or edge with given reference.

Preprocessor ** QUALXX** verifies that all the elements in a two-dimensional mesh have positive surfaces. It also
ascertains the element quality of a mesh.

For the three-dimensional case, the verification for positiveness of the element volumes is done whereas the quality is only calculated for tetrahedral type elements.

The module called is QUALNO. The element computational subroutines are: MESELE for a triangle, MESELQ for a quadrilateral, and MESELT for a tetrahedron (MESELP and MESELH for a pentahedron and a hexahedron). These subroutines evaluates the element surface (volume). In essence, the formula to calculate the quality of a triangle is the following:

where is a normalization coefficient ( is set equal to in such a way that
**Q=1.** for a equilateral triangle), **h** is the diameter of the element and is the radius of
the inscribed circle. This formula can be expressed as:

where **p** is the semi-perimeter and **S** is the surface of the triangle. For simplicity, we use
the same formula in the case of a quadrilateral (the result is not exact but the elements are
compared with each other without difficulty. On could undoubtedly find better!). For a tetrahedron,
the formula is analogous (and therefore exact) to that of the triangle.

Note that the higher the value of **Q**, the worse the element.

- Remark: QUALXX
- replaces
**GEODXX**, which has been discarded.