TRIANGULATION_TRIANGLE_NEIGHBORS is a FORTRAN90 program which computes the three neighboring triangles of each triangle in a triangulation.
The user supplies a node file and a triangle file, containing the coordinates of the nodes, and the indices of the nodes that make up each triangle. Either 3-node or 6-node triangles may be used.
The program reads the data, computes the triangle neighbor information, and writes out the information to a file. In cases where one side of a triangle has no triangle neighbor, a value of -1 is assigned.
The triangle neighbor array is useful if the triangulation has to be searched to find the triangle containing a given point. It is also useful when analyzing the bandwidth of the adjacency matrix, or of a finite element matrix derived from the triangulation.
triangulation_triangle_neighbors prefixwhere prefix is the common prefix for the node and triangle files, and will also be used to name the output file:
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
TRIANGULATION_TRIANGLE_NEIGHBORS is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version.
MESH_BANDWIDTH, a FORTRAN90 program which returns the geometric bandwidth associated with a mesh of elements of any order and in a space of arbitrary dimension.
MESH_TO_XML, a FORTRAN90 program which reads information defining a 1D, 2D or 3D mesh, namely a file of node coordinates and a file of elements defined by node indices, and creates a corresponding XML file for input to DOLFIN or FENICS.
NEIGHBORS_TO_METIS_GRAPH, a FORTRAN90 program which reads a triangle mesh neighbor file created by TRIANGULATION_TRIANGLE_NEIGHBORS and writes a modified version of the same data suitable for input to the mesh partitioning program METIS.
RCM, a FORTRAN90 library which carries out reverse Cuthill-McKee computations.
TABLE_DELAUNAY, a FORTRAN90 program which triangulates a set of nodes whose coordinates are stored in a file.
TET_MESH_RCM, a FORTRAN90 library which applies the reverse Cuthill-McKee reordering to a tetrahedral mesh of nodes in 3D.
TRIANGLE, a C program which computes a triangulation of a geometric region.
TRIANGULATION, a FORTRAN90 library which carries out various operations on order 3 ("linear") or order 6 ("quadratic") triangulations.
TRIANGULATION_BOUNDARY_NODES, a FORTRAN90 program which reads data defining a triangulation, determines which nodes lie on the boundary, and writes their coordinates to a file.
TRIANGULATION_CORNER, a FORTRAN90 program which patches triangulations so that no triangle has two sides on the boundary.
TRIANGULATION_DELAUNAY_DISCREPANCY, a FORTRAN90 program which measures the amount by which a triangulation fails the local Delaunay test;
TRIANGULATION_DISPLAY_OPENGL, a C++ program which reads files defining a triangulation and displays an image using Open GL.
TRIANGULATION_HISTOGRAM, a FORTRAN90 program which computes histograms of data over a triangulation.
TRIANGULATION_L2Q, a FORTRAN90 program which reads data defining a 3-node triangulation and generates midside nodes and writes out the corresponding 6-node triangulation.
TRIANGULATION_MASK, a FORTRAN90 program which takes an existing triangulation and deletes triangles and their corresponding nodes as requested by the user.
TRIANGULATION_ORDER3, a directory which contains a description and examples of order 3 triangulations.
TRIANGULATION_ORDER6, a directory which contains a description and examples of order 6 triangulations.
TRIANGULATION_ORIENT, a FORTRAN90 program which reads data defining a triangulation, makes sure that every triangle has positive orientation, and if not, writes a corrected triangle file.
TRIANGULATION_PLOT, a FORTRAN90 program which reads data defining a triangulation and creates a PostScript image of the nodes and triangles.
TRIANGULATION_Q2L, a FORTRAN90 program which reads data defining a 6-node triangulation, and subdivides each triangle into 4 3-node triangles, writing the resulting triangulation to a file.
TRIANGULATION_QUAD, a FORTRAN90 program which estimates the integral of a function over a triangulated region.
TRIANGULATION_QUALITY, a FORTRAN90 program which reads data defining a triangulation and computes a number of quality measures.
TRIANGULATION_RCM, a FORTRAN90 program which can reorder the nodes of a triangulation so that the bandwidth of the associated adjacency matrix is reduced.
TRIANGULATION_REFINE, a FORTRAN90 program which can be used to refine a triangulation.
TRIG_TO_NEIB, a C program which reads "NODE" and "ELE" files (a format prescribed by triangle) describing a triangulation, and produces a file defining the neighbor triangles of each element; the program can also produce information about the Voronoi diagram. The program is by Lili Ju.
BIG_CAVITY is a triangulation using 8,195 nodes and 4,000 elements.
BOX3 is a triangulation of order 3, using 20 nodes and 24 elements:
BOX6 is a triangulation of order 6:
GREENLAND is a triangulation using 33,343 nodes and 64,125 elements.
LAKE_COARSE is an irregular lake with an island.
There are 621 nodes and 974 elements and 1 hole.
LAKE3 is an irregular lake with an island.
The smallest angle is 23.46 degrees.
There are 1552 nodes and 2820 elements and 1 hole.
You can go up one level to the FORTRAN90 source codes.