FEM2D_SCALAR_DISPLAY_GPL
Surface Plot of FEM2D Data Using GNUPLOT

FEM2D_SCALAR_DISPLAY_GPL, a MATLAB program which reads datafiles describing a set of nodes, their triangulation, and the value of a scalar quantity at each node, and creates a graphics file of the corresponding surface plot, which can be displayed by GNUPLOT.

The program reads three data files:

prefix_nodes.txt, a node file, containing X, Y coordinates of points;
prefix_elements.txt, an element file, containing a list of sets of three points making up each triangular element; (if this file does not exist, the program will generate the element data automatically).
prefix_values.txt, a values file, containing the values of a scalar function U(X,Y) evaluated at each node.

Usage:

fem2d_scalar_display_gpl ( 'prefix' )

where 'prefix' is the common prefix for the node, element and value files:

The program creates two files:

prefix_data.txt, containing data;
prefix_commands.txt, containing commands for GNUPLOT.

To actually create the plot, type

gnuplot < prefix_commands.txt

which will create the file prefix.png

Licensing:

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

Languages:

FEM2D_SCALAR_DISPLAY_GPL is available in a MATLAB version.

Related Data and Programs:

DIST_PLOT, a MATLAB program which makes contour plots of the distance function, as defined and used in Persson and Strang's distmesh code;

FEM2D_MESH_DISPLAY, a MATLAB program which reads the FEM model of a 2D mesh, consisting of polygonal elements of any uniform order, and displays an image of the elements and nodes, with optional numbering.

FEM2D_SCALAR_DISPLAY, a MATLAB program which reads information about nodes, elements and nodal values for a 2D finite element method (FEM) and creates a surface plot of U(X,Y), using the MATLAB graphics system.

FEM2D_SCALAR_DISPLAY_BRIEF, a MATLAB program which reads information about nodes, elements and nodal values for a 2D finite element method (FEM) and creates a surface plot of U(X,Y), using the MATLAB graphics system, in 5 lines of code.

fem2d_scalar_display_gpl_test

FENICS_TO_FEM, examples which illustrate how a mesh or scalar function computed by the FENICS program can be written to FEM files, which can then be used to create images, or as input to meshing programs or other analysis tools.

GNUPLOT, examples which illustrate the use of the gnuplot graphics program.

GPL, a data directory which contains examples of GPL files, a graphics file format used by gnuplot;

GPL_DISPLAY, a MATLAB library which tries to read the data in a typical gnuplot GPL file, and display it in a more attractive way than gnuplot is capable of.

TRIANGULATION_ORDER3_CONTOUR, a MATLAB program which can display a contour plot of scalar data defined on a triangulation of order 3.

Source Code:

fem2d_scalar_display_gpl.m, the routine for creating the surface plot;
timestamp.m, prints the YMDHMS date as a timestamp;