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<html>
<head>
<title>
TET_MESH_Q2L - 10-Node Tet Mesh to 4-Node Tet Mesh
</title>
</head>
<body bgcolor="#EEEEEE" link="#CC0000" alink="#FF3300" vlink="#000055">
<h1 align = "center">
TET_MESH_Q2L <br> 10-Node Tet Mesh <br>
to <br>
4-Node Tet Mesh
</h1>
<hr>
<p>
<b>TET_MESH_Q2L</b>
is a FORTRAN90 program which
reads information
describing a tet mesh of a set of points using 10-node
("quadratic") triangles, and creates a 4-node ("linear")
tet mesh.
</p>
<p>
The same nodes are used, but each 10-node tetrahedron is broken
up into 8 smaller 4-node tetrahedrons.
</p>
<h3 align = "center">
Usage:
</h3>
<p>
<blockquote>
<b>tet_mesh_q2l</b> <i>prefix</i>
</blockquote>
where <i>prefix</i> is the common file prefix:
<ul>
<li>
<i>prefix</i><b>_nodes.txt</b>, the node coordinates (not needed by this program);
</li>
<li>
<i>prefix</i><b>_elements.txt</b>, the element definitions.
</li>
<li>
<i>prefix</i><b>_q2l_elements.txt</b>, the linear element definitions created
by this program, and based on the same set of nodes.
</li>
</ul>
</p>
<p>
The input and output files use the simple
<a href = "../../data/table/table.html">TABLE format</a>;
comment lines begin with a "#" character. Otherwise, each line
of the file contains one set of information, either the coordinates
of a node (for a node file), or the indices of nodes that make up
a tetrahedron, (for a tetrahedron file).
</p>
<p>
The input file <i>tetras.txt</i> contains the tetrahedron information
for the 10-node tet mesh. Each line contains the indices
of 10 nodes that form a tetrahedron, in a particular order.
The first 4 indices are the vertices. Subsequent nodes can be
described by the pair of vertices they lie between, as follows:
<pre>
1 2 3 4 (1+2) (1+3) (1+4) (2+3) (2+4) (3+4)
</pre>
</p>
<p>
The output file <i>tetras.l2q.txt</i> contains the tetrahedron
information for the 4-node tet mesh.
</p>
<h3 align = "center">
Licensing:
</h3>
<p>
The computer code and data files described and made available on this web page
are distributed under
<a href = "../../txt/gnu_lgpl.txt">the GNU LGPL license.</a>
</p>
<h3 align = "center">
Languages:
</h3>
<p>
<b>TET_MESH_Q2L</b> is available in
<a href = "../../cpp_src/tet_mesh_q2l/tet_mesh_q2l.html">a C++ version</a> and
<a href = "../../f_src/tet_mesh_q2l/tet_mesh_q2l.html">a FORTRAN90 version</a> and
<a href = "../../m_src/tet_mesh_q2l/tet_mesh_q2l.html">a MATLAB version</a>.
</p>
<h3 align = "center">
Related Programs:
</h3>
<p>
<a href = "../../f_src/cvt_tet_mesh/cvt_tet_mesh.html">
CVT_TET_MESH</a>,
a FORTRAN90 library which
uses CVT methods to compute a tet mesh in a region.
</p>
<p>
<a href = "../../f_src/geompack/geompack.html">
GEOMPACK</a>,
a FORTRAN90 library which
contains a routine
<b>DTRIS3</b> that can compute the tet mesh for a set of 3D points,
as well as the adjacency information.
</p>
<p>
<a href = "../../f_src/table_tet_mesh/table_tet_mesh.html">
TABLE_TET_MESH</a>,
a FORTRAN90 program which
can compute the tet mesh
for a given set of points.
</p>
<p>
<a href = "../../f_src/test_tet_mesh/test_tet_mesh.html">
TEST_TET_MESH</a>,
a FORTRAN90 library which
defines a few test regions for the generation
of a tet mesh.
</p>
<p>
<a href = "../../f_src/tet_mesh/tet_mesh.html">
TET_MESH</a>,
a FORTRAN90 library which
includes a variety of routines for working
with tetrahedral meshes.
</p>
<p>
<a href = "../../m_src/tet_mesh_display/tet_mesh_display.html">
TET_MESH_DISPLAY</a>,
a MATLAB program which reads the node and tetra files defining a tet mesh
and displays a wireframe image.
</p>
<p>
<a href = "../../cpp_src/tet_mesh_display_opengl/tet_mesh_display_opengl.html">
TET_MESH_DISPLAY_OPENGL</a>,
a C++ program which
reads a tet mesh and displays the nodes and edges using OpenGL.
</p>
<p>
<a href = "../../f_src/tet_mesh_l2q/tet_mesh_l2q.html">
TET_MESH_L2Q</a>,
a FORTRAN90 program which
takes a 4-node tet mesh and makes
a 10-node tet mesh, by inserting new nodes.
</p>
<p>
<a href = "../../data/tet_mesh_order4/tet_mesh_order4.html">
TET_MESH_ORDER4</a>,
a directory which
contains a description and
examples of a tet mesh using order 4 elements.
</p>
<p>
<a href = "../../data/tet_mesh_order10/tet_mesh_order10.html">
TET_MESH_ORDER10</a>,
a directory which
contains a description and
examples of a tet mesh using order 10 elements.
</p>
<p>
<a href = "../../f_src/tet_mesh_quality/tet_mesh_quality.html">
TET_MESH_QUALITY</a>,
a FORTRAN90 program which
computes the "quality" of a mesh.
</p>
<p>
<a href = "../../f_src/tet_mesh_rcm/tet_mesh_rcm.html">
TET_MESH_RCM</a>,
a FORTRAN90 program which
takes a 4-node or 10-node tet mesh and
relabels the nodes to reduce the bandwidth of the
corresponding adjacency matrix.
</p>
<p>
<a href = "../../f_src/tet_mesh_refine/tet_mesh_refine.html">
TET_MESH_REFINE</a>,
a FORTRAN90 program which
can refine a tet mesh.
</p>
<p>
<a href = "../../f_src/tet_mesh_tet_neighbors/tet_mesh_tet_neighbors.html">
TET_MESH_TET_NEIGHBORS</a>,
a FORTRAN90 program which
computes the tetrahedral adjacency information.
</p>
<p>
<a href = "../../f_src/tet_mesh_volumes/tet_mesh_volumes.html">
TET_MESH_VOLUMES</a>,
a FORTRAN90 program which
computes the volume of each tetrahedron in a tet mesh;
</p>
<p>
<a href = "../../f_src/tetrahedron_properties/tetrahedron_properties.html">
TETRAHEDRON_PROPERTIES</a>,
a FORTRAN90 program which
computes properties of a given tetrahedron.
</p>
<p>
<a href = "../../datasets/tetrahedrons/tetrahedrons.html">
TETRAHEDRONS</a>,
a dataset directory which
contains examples of tetrahedrons;
</p>
<h3 align = "center">
Reference:
</h3>
<p>
<ol>
<li>
Herbert Edelsbrunner,<br>
Geometry and Topology for Mesh Generation,<br>
Cambridge, 2001,<br>
ISBN: 0-521-79309-2,<br>
LC: QA377.E36.
</li>
<li>
Barry Joe,<br>
GEOMPACK - a software package for the generation of meshes
using geometric algorithms,<br>
Advances in Engineering Software,<br>
Volume 13, 1991, pages 325-331.
</li>
<li>
Anwei Liu, Barry Joe,<br>
Quality Local Refinement of Tetrahedral Meshes Based
on 8-Subtetrahedron Subdivision,<br>
Mathematics of Computation,<br>
Volume 65, Number 215, July 1996, pages 1183-1200.
</li>
<li>
Per-Olof Persson, Gilbert Strang,<br>
A Simple Mesh Generator in MATLAB,<br>
SIAM Review,<br>
Volume 46, Number 2, June 2004, pages 329-345.
</li>
</ol>
</p>
<h3 align = "center">
Source code:
</h3>
<p>
<ul>
<li>
<a href = "tet_mesh_q2l.f90">tet_mesh_q2l.f90</a>,
the source code.
</li>
<li>
<a href = "tet_mesh_q2l.sh">tet_mesh_q2l.sh</a>,
commands to compile the source code.
</li>
</ul>
</p>
<h3 align = "center">
Examples and Tests:
</h3>
<p>
You may copy data for an example problem:
<ul>
<li>
<a href = "cube_nodes.txt">cube_nodes.txt</a>,
a set of nodes.
</li>
<li>
<a href = "cube_elements.txt">cube_elements.txt</a>,
the elements for a 10-node tet mesh of the nodes.
</li>
<li>
<a href = "cube_output.txt">cube_output.txt</a>,
the printed output.
</li>
<li>
<a href = "cube_q2l_elements.txt">cube_q2l_elements.txt</a>,
the elements for a 4-node tet mesh derived from the
quadratic mesh.
</li>
</ul>
</p>
<h3 align = "center">
List of Routines:
</h3>
<p>
<ul>
<li>
<b>MAIN</b> is the main program for TET_MESH_Q2L.
</li>
<li>
<b>CH_CAP</b> capitalizes a single character.
</li>
<li>
<b>CH_EQI</b> is a case insensitive comparison of two characters for equality.
</li>
<li>
<b>CH_TO_DIGIT</b> returns the integer value of a base 10 digit.
</li>
<li>
<b>FILE_COLUMN_COUNT</b> counts the number of columns in the first line of a file.
</li>
<li>
<b>FILE_ROW_COUNT</b> counts the number of row records in a file.
</li>
<li>
<b>GET_UNIT</b> returns a free FORTRAN unit number.
</li>
<li>
<b>I4MAT_DATA_READ</b> reads data from an I4MAT file.
</li>
<li>
<b>I4MAT_HEADER_READ</b> reads the header from an I4MAT.
</li>
<li>
<b>I4MAT_TRANSPOSE_PRINT_SOME</b> prints some of the transpose of an I4MAT.
</li>
<li>
<b>I4MAT_WRITE</b> writes an I4MAT file.
</li>
<li>
<b>S_INDEX_LAST</b> finds the LAST occurrence of a given substring.
</li>
<li>
<b>S_TO_I4</b> reads an I4 from a string.
</li>
<li>
<b>S_TO_I4VEC</b> reads an I4VEC from a string.
</li>
<li>
<b>S_WORD_COUNT</b> counts the number of "words" in a string.
</li>
<li>
<b>TET_MESH_ORDER10_TO_ORDER4_COMPUTE</b> linearizes a quadratic tet mesh.
</li>
<li>
<b>TET_MESH_ORDER10_TO_ORDER4_SIZE</b> sizes a linear tet mesh from a quadratic one.
</li>
<li>
<b>TIMESTAMP</b> prints the current YMDHMS date as a time stamp.
</li>
</ul>
</p>
<p>
You can go up one level to <a href = "../f_src.html">
the FORTRAN90 source codes</a>.
</p>
<hr>
<i>
Last revised on 30 September 2009.
</i>
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