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<html>
<head>
<title>
FREEFEM++_MSH_IO - Read and Write FreeFem++ MSH files
</title>
</head>
<body bgcolor="#EEEEEE" link="#CC0000" alink="#FF3300" vlink="#000055">
<h1 align = "center">
FREEFEM++_MSH_IO <br> Read and Write FreeFem++ MSH files
</h1>
<hr>
<p>
<b>FREEFEM++_MSH_IO</b>,
a C++ library which
can read and write files used by the FreeFem++ finite element program
to store mesh information.
</p>
<p>
Note that the GMSH program creates mesh files that use the ".msh"
extension, but which are an entirely different format.
</p>
<p>
The msh file format is obliquely described in section 12.5 of the
FreeFem++ documentation.
<p>
<p>
At least for the 2D case of a triangular mesh, the format seems
to be as follows:
<ol>
<li>
a single line giving NV, NE, NT, the number of vertices, boundary edges, and triangles
</li>
<li>
NV lines, each containing the (X,Y) coordinates and integer label for a node.
</li>
<li>
NT lines, each containing three vertex indices and integer label for a triangle.
</li>
<li>
NE lines, each containing two vertex indices and integer label for a boundary edge.
</li>
</ol>
The "labels" seem to be "0" for interior objects and 1 for boundary objects.
All edges are boundary objects. (This might not be true. A geometry
might include internal edges, and perhaps these count as interior objects,
but definitely, the edge list does not include arbitrary triangle edges,
only those on the boundary.) All triangles are interior objects.
Vertices may be boundary or interior objects.
<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>FREEFEM++_MSH_IO</b> is available in
<a href = "../../c_src/freefem++_msh_io/freefem++_msh_io.html">a C version</a> and
<a href = "../../cpp_src/freefem++_msh_io/freefem++_msh_io.html">a C++ version</a> and
<a href = "../../f77_src/freefem++_msh_io/freefem++_msh_io.html">a FORTRAN77 version</a> and
<a href = "../../f_src/freefem++_msh_io/freefem++_msh_io.html">a FORTRAN90 version</a> and
<a href = "../../m_src/freefem++_msh_io/freefem++_msh_io.html">a MATLAB version</a> and
<a href = "../../py_src/freefem++_msh_io/freefem++_msh_io.html">a Python version</a>.
</p>
<h3 align = "center">
Related Data and Programs:
</h3>
<p>
<a href = "../../examples/bamg/bamg.html">
BAMG</a>,
examples which
illustrate the use of BAMG,
a program for generating 2D meshes that can be used to
define the geometry for the the finite element package FREEFEM++.
</p>
<p>
<a href = "../../examples/freefem++/freefem++.html">
FREEFEM++</a>,
examples which
illustrate the use of the FREEFEM++ package,
a high-level integrated development environment for the numerical
solution of nonlinear multiphysics partial differential equations (PDE's)
in 2D and 3D.
</p>
<p>
<a href = "../../data/freefem++_msh/freefem++_msh.html">
FREEFEM++_MSH</a>,
a data directory which
contains examples of the mesh files created by the FreeFem++ program,
which use the extension ".msh".
</p>
<p>
<a href = "../../examples/mitchell_freefem++/mitchell_freefem++.html">
MITCHELL_FREEFEM++</a>,
examples which
illustrate the implementation of the Mitchell 2D elliptic
partial differential equation (PDE) test problems using FREEFEM++.
</p>
<h3 align = "center">
Reference:
</h3>
<p>
<ol>
<li>
Frederic Hecht,<br>
New development in FreeFem++,<br>
Journal of Numerical Mathematics,<br>
Volume 20, Number 3-4, 2012, pages 251-265.
</li>
<li>
Frederic Hecht,<br>
BAMG: Bidimensional Anisotropic Mesh Generator,<br>
draft version v1.00, December 2006.
</li>
</ol>
</p>
<h3 align = "center">
Source Code:
</h3>
<p>
<ul>
<li>
<a href = "ffmsh_io.cpp">ffmsh_io.cpp</a>, the source code.
</li>
<li>
<a href = "ffmsh_io.hpp">ffmsh_io.hpp</a>, the include file.
</li>
<li>
<a href = "ffmsh_io.sh">ffmsh_io.sh</a>,
BASH commands to compile the source code.
</li>
</ul>
</p>
<h3 align = "center">
Examples and Tests:
</h3>
<p>
<ul>
<li>
<a href = "ffmsh_io_prb.cpp">ffmsh_io_prb.cpp</a>,
a sample calling program.
</li>
<li>
<a href = "ffmsh_io_prb.sh">ffmsh_io_prb.sh</a>,
BASH commands to compile and run the sample program.
</li>
<li>
<a href = "ffmsh_io_prb_output.txt">ffmsh_io_prb_output.txt</a>,
the output file.
</li>
<li>
<a href = "input.msh">input.msh</a>,
a FreeFem++ file read by the program.
</li>
<li>
<a href = "output.msh">output.msh</a>,
a FreeFem++ file written by the program.
</li>
</ul>
</p>
<h3 align = "center">
List of Routines:
</h3>
<p>
<ul>
<li>
<b>CH_CAP</b> capitalizes a single character.
</li>
<li>
<b>CH_EQI</b> is TRUE (1) if two characters are equal, disregarding case.
</li>
<li>
<b>CH_TO_DIGIT</b> returns the integer value of a base 10 digit.
</li>
<li>
<b>FFMSH_2D_DATA_EXAMPLE</b> returns example FFMSH data.
</li>
<li>
<b>FFMSH_2D_DATA_PRINT</b> prints FFMSH data.
</li>
<li>
<b>FFMSH_2D_DATA_READ</b> reads data from an FFMSH file.
</li>
<li>
<b>FFMSH_2D_SIZE_EXAMPLE</b> returns sizes for the 2D example.
</li>
<li>
<b>FFMSH_2D_SIZE_PRINT</b> prints the sizes of an FFMSH.
</li>
<li>
<b>FFMSH_2D_SIZE_READ</b> reads sizes from a FFMSH file.
</li>
<li>
<b>FFMSH_2D_WRITE</b> writes FFMSH data to a file.
</li>
<li>
<b>I4MAT_COPY</b> copies one I4MAT to another.
</li>
<li>
<b>I4MAT_TRANSPOSE_PRINT</b> prints an I4MAT, transposed.
</li>
<li>
<b>I4MAT_TRANSPOSE_PRINT_SOME</b> prints some of an I4MAT, transposed.
</li>
<li>
<b>I4VEC_COPY</b> copies an I4VEC.
</li>
<li>
<b>I4VEC_PRINT</b> prints an I4VEC.
</li>
<li>
<b>MESH_BASE_ONE</b> ensures that the element definition is one-based.
</li>
<li>
<b>R8MAT_COPY</b> copies one R8MAT to another.
</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_LEN_TRIM</b> returns the length of a string to the last nonblank.
</li>
<li>
<b>S_TO_I4</b> reads an I4 from a string.
</li>
<li>
<b>S_TO_R8</b> reads an R8 from 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 22 December 2014.
</i>
<!-- John Burkardt -->
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