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TET_MESH_VOLUMES\ Compute Tetrahedral Volumes in a Tet Mesh {#tet_mesh_volumes-compute-tetrahedral-volumes-in-a-tet-mesh align=”center”} =========================================

TET_MESH_VOLUMES is a C++ program which computes the volume of every tetrahedron in a tet mesh.

Usage: {#usage align=”center”}

tet_mesh_volume prefix

where prefix is the common file prefix:

prefix_nodes.txt, the node coordinates;
prefix_elements.txt, the element definitions.
prefix_volumes.txt, will contain the element volumes.

The element definition file will list node indices. In C++, it may be more natural to use 0-based indices. This program will accept an element definition file that is 0-based or 1-based, and will convert a 1-based input file so that it becomes 0-based internal to the program. The detection of 1-based data is determined by the absence of the use of a 0 index, and the use of an index equal to the number of nodes. This is an implicit and fallible, but reasonable, way to handle this problem.

Licensing: {#licensing align=”center”}

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

Languages: {#languages align=”center”}

TET_MESH_VOLUMES is available in a C++ version and a FORTRAN90 version and a MATLAB version.

TET_MESH, a C++ library which carries out various operations on tetrahedral meshes.

TET_MESH_BOUNDARY, a C++ program which returns the nodes and faces of the boundary of a tetrahedral mesh, which themselves form a 3D triangular mesh or “TRI_SURFACE”.

TET_MESH_DISPLAY, a MATLAB program which reads in the node and tetra files defining a tet mesh and displays a wireframe image.

TET_MESH_DISPLAY_OPENGL, a C++ program which reads a 3D tet mesh and displays the nodes and edges using OpenGL.

TET_MESH_L2Q, a C++ program which reads information about a 4-node (linear) tet mesh and creates data defining a corresponding 10-node (quadratic) tet mesh;

TET_MESH_ORDER4, a data directory which contains a description of a linear tet mesh of a set of 3D points, using a pair of files to list the node coordinates and the 4 nodes that make up each tetrahedron;

TET_MESH_ORDER4, a dataset directory which contains examples of order 4 tetrahedral meshes.

TET_MESH_ORDER10, a data directory which contains a description of a quadratic tet mesh of a set of 3D points, using a pair of files to list the node coordinates and the 10 nodes that make up each tetrahedron;

TET_MESH_ORDER10, a dataset directory which contains examples of order 10 tetrahedral meshes.

TET_MESH_Q2L, a C++ program which reads information about a 10-node (quadratic) tet mesh and creates data defining a corresponding 4-node (linear) tet mesh;

TET_MESH_QUALITY, a C++ program which computes quality measures of a tetrahedral mesh.

TET_MESH_RCM, a C++ program which computes the reverse Cuthill-McKee reordering for the nodes of a tet mesh that uses 4-node or 10-node tetrahedrons;

TET_MESH_REFINE, a C++ program which refines a tet mesh;

TET_MESH_TET_NEIGHBORS, a data directory which contains examples of TET_MESH_TET_NEIGHBOR files, description of a format for tetrahedron adjacency information in a tetrahedral mesh of 3D points;

TET_MESH_TET_NEIGHBORS, a C++ program which reads information about a tet mesh and writes out a list of the tetrahedrons that are adjacent to a given tetrahedron;

Source Code: {#source-code align=”center”}

tet_mesh_volumes.cpp, the source code.

Examples and Tests: {#examples-and-tests align=”center”}

CUBE is the 8 vertices of the unit cube [0,1]x[0,1]x[0,1], defining 6 elements of equal volume but not equal shape.

cube_nodes.txt, the node coordinate file.
cube_elements.txt, the element file.
cube.png, a PNG image of the mesh.
cube_volumes.txt, the volume file.

TWENTY is 20 random nodes, defining 70 elements.

twenty_nodes.txt, the node coordinate file.
twenty_elements.txt, the element file.
twenty.png, a PNG image of the mesh.
twenty_volumes.txt, the volume file.

List of Routines: {#list-of-routines align=”center”}

MAIN is the main program for TET_MESH_QUALITY.
CH_CAP capitalizes a single character.
CH_EQI is a case insensitive comparison of two characters for equality.
CH_TO_DIGIT returns the integer value of a base 10 digit.
FILE_COLUMN_COUNT counts the number of columns in the first line of a file.
FILE_EXIST reports whether a file exists.
FILE_ROW_COUNT counts the number of row records in a file.
GET_UNIT returns a free FORTRAN unit number.
I4MAT_DATA_READ reads data from an I4MAT file.
I4MAT_HEADER_READ reads the header from an I4MAT.
I4MAT_TRANSPOSE_PRINT_SOME prints some of the transpose of an I4MAT.
R8MAT_DATA_READ reads data from an R8MAT file.
R8MAT_DET_4D computes the determinant of a 4 by 4 matrix.
R8MAT_HEADER_READ reads the header from an R8MAT file.
R8MAT_TRANSPOSE_PRINT_SOME prints some of an R8MAT, transposed.
R8MAT_WRITE writes an R8MAT file.
R8VEC_PRINT prints an R8VEC.
R8VEC_VARIANCE returns the variance of an R8VEC.
S_TO_I4 reads an I4 from a string.
S_TO_I4VEC reads an I4VEC from a string.
S_TO_R8 reads an R8 from a string.
S_TO_R8VEC reads an R8VEC from a string.
S_WORD_COUNT counts the number of “words” in a string.
TETRAHEDRON_VOLUME_3D computes the volume of a tetrahedron in 3D.
TIMESTAMP prints the current YMDHMS date as a time stamp.

You can go up one level to the C++ source codes.

Last revised on 13 August 2009.