FEM_TO_TRIANGLE
Convert a Mesh from FEM to Triangle Format

FEM_TO_TRIANGLE is a FORTRAN77 program which reads FEM files of node coordinates and element connectivity, which define a mesh of a 2D region, divided into triangular elements, and creates a corresponding pair of Triangle files.

These files can be used as input to Triangle for viewing, or mesh refinement.

Usage:

fem_to_triangle prefix

• 'prefix'_nodes.txt contains the node coordinates,
• 'prefix'_elements.txt contains the element definitions.
• 'prefix'.node will be the Triangle node file.
• 'prefix'.ele will be the Triangle element file.

Licensing:

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

Languages:

FEM_TO_TRIANGLE is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version.

Related Data and Programs:

FEM_IO, a FORTRAN77 library which reads or writes node, element and data files defining a model associated with the finite element method (FEM).

FEM_TO_GMSH, a FORTRAN77 program which reads FEM files definining a 1D, 2D or 3D mesh, namely a file of node coordinates and a file of elements defined by node indices, and creates a Gmsh mesh file.

FEM_TO_MEDIT, a FORTRAN77 program which reads a pair of FEM files defining node coordinates and elements, and creates a corresponding MEDIT mesh file.

FEM_TO_XML, a FORTRAN77 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.

FEM2D, a data directory which contains examples of 2D FEM files, text files that describe a 2D geometry and node values associated with the finite element method (FEM);

TRIANGLE_FILES, a data directory which contains examples of files used by the triangle() and showme() programs.

TRIANGLE_IO, a FORTRAN77 library which can read or write some of the files created by Jonathan Shewchuk's triangle() program.

Source Code:

• fem_to_triangle.f, the source code.
• fem_to_triangle.sh, commands to compile the source code.

Examples and Tests:

ELL is an L-shaped region with 65 nodes and 96 elements.

• ell_nodes.txt, the node coordinates in FEM format.
• ell_elements.txt, the elements in FEM format.
• ell.node, the node coordinates in TRIANGLE format.
• ell.ele, the elements in TRIANGLE format.

List of Routines:

• MAIN is the main program for FEM_TO_TRIANGLE.
• CH_CAP capitalizes a single character.
• CH_EQI is a case insensitive comparison of two characters for equality.
• CH_TO_DIGIT returns the value of a base 10 digit.
• FILE_COLUMN_COUNT counts the number of columns in the first line of a file.
• 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 prints an I4MAT, transposed.
• I4MAT_TRANSPOSE_PRINT_SOME prints some of the transpose of an I4MAT.
• MESH_BASE_ZERO ensures that the element definition is zero-based.
• R8MAT_DATA_READ reads data from an R8MAT file.
• R8MAT_HEADER_READ reads the header from an R8MAT file.
• R8MAT_TRANSPOSE_PRINT prints an R8MAT, transposed.
• R8MAT_TRANSPOSE_PRINT_SOME prints some of an R8MAT, transposed.
• 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.
• TIMESTAMP prints the current YMDHMS date as a time stamp.
• TRIANGLE_ELEMENT_WRITE writes a TRIANGLE ".ele" file.
• TRIANGLE_NODE_WRITE writes a TRIANGLE ".node" file.

You can go up one level to the FORTRAN77 source codes.