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fem_to_gmsh.html
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<html>
<head>
<title>
FEM_TO_GMSH - Convert Mesh Data from FEM to GMSH Format
</title>
</head>
<body bgcolor="#EEEEEE" link="#CC0000" alink="#FF3300" vlink="#000055">
<h1 align = "center">
FEM_TO_GMSH <br> Convert Mesh Data from FEM to GMSH Format
</h1>
<hr>
<p>
<b>FEM_TO_GMSH</b>
is a C++ program which
converts FEM files representing a 1D, 2D, or 3D mesh into a
GMSH mesh file.
</p>
<p>
The FEM files include a node file, which simply lists the coordinates
of each node, and an element connectivity file, which lists, for each
element, the indices of the nodes that define it. Either 0 or 1-based
indexing can be used when referencing the nodes.
</p>
<h3 align = "center">
Usage:
</h3>
<p>
<blockquote>
<b>fem_to_gmsh</b> <i>prefix</i>
</blockquote>
where <i>prefix</i> is the common filename prefix:
<ul>
<li>
<i>'prefix'</i>_nodes.txt contains the node coordinates,
</li>
<li>
<i>'prefix'</i>_elements.txt contains the element node connectivity.
</li>
<li>
<i>'prefix'</i>.msh will contain the Gmsh mesh file.
</li>
</ul>
</p>
<h3 align = "center">
Licensing:
</h3>
<p>
The computer code and data files 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>FEM_TO_GMSH</b> is available in
<a href = "../../c_src/fem_to_gmsh/fem_to_gmsh.html">a C version</a> and
<a href = "../../cpp_src/fem_to_gmsh/fem_to_gmsh.html">a C++ version</a> and
<a href = "../../f77_src/fem_to_gmsh/fem_to_gmsh.html">a FORTRAN77 version</a> and
<a href = "../../f_src/fem_to_gmsh/fem_to_gmsh.html">a FORTRAN90 version</a> and
<a href = "../../m_src/fem_to_gmsh/fem_to_gmsh.html">a MATLAB version</a>.
</p>
<h3 align = "center">
Related Data and Programs:
</h3>
<p>
<a href = "../../py_src/dolfin-convert/dolfin-convert.html">
DOLFIN-CONVERT</a>,
a Python program which
can convert mesh file from Gmsh, MEDIT, METIS or SCOTCH format to an
XML format suitable for use by DOLFIN or FENICS,
by Anders Logg.
</p>
<p>
<a href = "../../cpp_src/fem_to_medit/fem_to_medit.html">
FEM_TO_MEDIT</a>,
a C++ program which
reads a pair of FEM files defining node coordinates and elements,
and creates a corresponding MEDIT mesh file.
</p>
<p>
<a href = "../../cpp_src/fem_to_triangle/fem_to_triangle.html">
FEM_TO_TRIANGLE</a>,
a C++ program which
reads FEM files defining a 2D mesh of triangles, namely
a file of node coordinates and a file of elements defined by
node indices, and creates a corresponding pair of node
and element files for use by Jonathan Shewchuk's triangle program.
</p>
<p>
<a href = "../../cpp_src/fem_to_xml/fem_to_xml.html">
FEM_TO_XML</a>,
a C++ program which
reads FEM files 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.
</p>
<p>
<a href = "../../examples/gmsh/gmsh.html">
GMSH</a>,
examples which
illustrate the use of the Gmsh program,
a 3D mesh generator for the finite element method (FEM).
</p>
<p>
<a href = "../../cpp_src/gmsh_io/gmsh_io.html">
GMSH_IO</a>,
a C++ library which
can read or write some of the files created by the Gmsh
program for 1D, 2D or 3D meshes used by the finite element method (FEM).
</p>
<p>
<a href = "../../cpp_src/gmsh_to_fem/gmsh_to_fem.html">
GMSH_TO_FEM</a>,
a C++ program which
reads a mesh data file created by the GMSH program
and writes a pair of node and element files that correspond
to the FEM format.
</p>
<p>
<a href = "../../data/msh/msh.html">
MSH</a>,
a data directory of examples of MSH files,
the native 3D mesh format used by Gmsh.
</p>
<h3 align = "center">
Reference:
</h3>
<p>
<ol>
<li>
Christophe Geuzaine, Jean-Francois Remacle,<br>
Gmsh: a three-dimensional finite element mesh generator with
built-in pre- and post-processing facilities,<br>
International Journal for Numerical Methods in Engineering,<br>
Volume 79, Number 11, pages 1309-1331, 2009.
</li>
</ol>
</p>
<h3 align = "center">
Source Code:
</h3>
<p>
<ul>
<li>
<a href = "fem_to_gmsh.cpp">fem_to_gmsh.cpp</a>,
the source code.
</li>
<li>
<a href = "fem_to_gmsh.sh">fem_to_gmsh.sh</a>,
commands to compile the source code.
</li>
</ul>
</p>
<h3 align = "center">
Examples and Tests:
</h3>
<p>
<b>CHEBY9</b> is a 1D interval, [-1,+1], containing 9 nodes and 8 elements.
<ul>
<li>
<a href = "cheby9_nodes.txt">cheby9_nodes.txt</a>,
the node coordinates.
</li>
<li>
<a href = "cheby9_elements.txt">cheby9_elements.txt</a>,
the elements.
</li>
<li>
<a href = "cheby9.msh">cheby9.msh</a>,
the corresponding GMSH mesh file.
</li>
</ul>
</p>
<p>
<b>MESH3D</b> is a 3D tetrahedral mesh using 8 nodes and 6 elements.
<ul>
<li>
<a href = "mesh3d_nodes.txt">mesh3d_nodes.txt</a>,
the nodes for the 4-node tet mesh.
</li>
<li>
<a href = "mesh3d_elements.txt">mesh3d_elements.txt</a>,
the elements for the 4-node tet mesh.
</li>
<li>
<a href = "mesh3d.msh">mesh3d.msh</a>,
the Gmsh msh file version of the data.
</li>
</ul>
</p>
<p>
<b>RECTANGLE</b> is a 2D rectangular region which has been divided
into 3 rows and 4 columns of squares, each then split into two
3-node triangles. The node and element files of this triangulation
are converted into a Gmsh msh file describing the same triangulation.
<ul>
<li>
<a href = "rectangle_nodes.txt">rectangle_nodes.txt</a>,
the node coordinates.
</li>
<li>
<a href = "rectangle_elements.txt">rectangle_elements.txt</a>,
the elements.
</li>
<li>
<a href = "rectangle.png">rectangle.png</a>,
a PNG image of the triangulation, created by TRIANGULATION_PLOT.
</li>
<li>
<a href = "rectangle.msh">rectangle.msh</a>,
the corresponding Gmsh msh file.
</li>
</ul>
</p>
<h3 align = "center">
List of Routines:
</h3>
<p>
<ul>
<li>
<b>MAIN</b> is the main program for FEM_TO_GMSH.
</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 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>GMSH_WRITE</b> writes the triangulation data as a Gmsh mesh file.
</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</b> prints an I4MAT, transposed.
</li>
<li>
<b>I4MAT_TRANSPOSE_PRINT_SOME</b> prints some of the transpose of an I4MAT.
</li>
<li>
<b>MESH_BASE_ONE</b> ensures that the element definition is one-based.
</li>
<li>
<b>R8MAT_DATA_READ</b> reads data from an R8MAT file.
</li>
<li>
<b>R8MAT_HEADER_READ</b> reads the header from an R8MAT file.
</li>
<li>
<b>R8MAT_TRANSPOSE_PRINT</b> prints an R8MAT, transposed.
</li>
<li>
<b>R8MAT_TRANSPOSE_PRINT_SOME</b> prints some of an R8MAT, transposed.
</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_TO_R8</b> reads an R8 from a string.
</li>
<li>
<b>S_TO_R8VEC</b> reads an R8VEC from a string.
</li>
<li>
<b>S_WORD_COUNT</b> counts the number of "words" in a string.
</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 = "../cpp_src.html">
the C++ source codes</a>.
</p>
<hr>
<i>
Last revised on 06 October 2014.
</i>
<!-- John Burkardt -->
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