**quad_mesh_test**,
a FORTRAN90 code which
calls quad_mesh(), which
carries out operations involving meshes of quadrilaterals.

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

quad_mesh, a FORTRAN90 code which handles meshes of quadrilaterals over a 2D region;

- quad_mesh_test.f90, a sample calling program.
- quad_mesh_test.sh, runs all the tests.
- quad_mesh_test.txt, the output file.

**EXAMPLE1** is a mesh made up of squares of uniform size. The squares
are arranged in a grid with a few irregularities, however. In particular,
there is an interior hole.

- q4_mesh_ex1_element_neighbors.txt, element neighbors for example 1 Q4 mesh.
- q4_mesh_ex1_elements.txt, elements for example 1 Q4 mesh.
- q4_mesh_ex1_xy.txt, node coordinates for example 1 Q4 mesh.
- q4_mesh_ex1.png, a PNG image of example 1 Q4 mesh.

**EXAMPLE2** is a mesh made up of quadrilaterals that are "trying" to tile a
semicircle. The row of elements that touches the origin is degenerate, and
are essentially triangles. The elements vary in area.

- q4_mesh_ex2_element_neighbors.txt, element neighbors for example 2 Q4 mesh.
- q4_mesh_ex2_elements.txt, elements for example 2 Q4 mesh.
- q4_mesh_ex2_xy.txt, node coordinates for example 2 Q4 mesh.
- q4_mesh_ex2.png, a PNG image of example 2 Q4 mesh.

**SAMPLE_QUAD** demonstrates how a single quadrilateral can be randomly sampled.

- sample_quad.txt, node coordinates for random sample points in a quadrilateral.
- sample_quad.png, a PNG image of the random sample points in a quadrilateral.