triangulation_order3_contour

triangulation_order3_contour, an Octave code which reads datafiles describing a set of nodes, their triangulation, and the value of a piecewise linear (PWL) scalar quantity at each node, and creates a color contour plot.

The program reads three data files:

• a node file, containing X, Y coordinates of points;
• 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).
• a values file, containing the values of a scalar function U(X,Y) evaluated at each node.

The program automatically displays three plots:

1. An line drawing of the triangulation;
2. A color contour plot with color constant over a triangle.
3. A color contour plot with color linearly interpolated to make a very nice picture.

Usage:

triangulation_order3_contour ( 'prefix' )

• 'prefix'_nodes.txt, lists the node coordinates;
• 'prefix'_elements.txt lists the indices of nodes that form elements (this file is optional, and if not supplied, the information will be generated internally);
• 'prefix'_values.txt contains the value assigned to each node.

Licensing:

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

Languages:

triangulation_order3_contour is available in a MATLAB version and an Octave version.

Related Data and Programs:

triangulation_order3_contour_test

dist_plot, an Octave code which makes contour plots of the distance function, as defined and used in Persson and Strang's distmesh() code;

fem, a data directory which contains a description and examples of the FEM format.

fem_basis_t3_display, an Octave code which displays a basis function associated with a linear triangle ("T3") mesh.

levels, an Octave code which makes a contour plot, choosing the contour levels using random sampling.

table, the data format which is used for each of the three input data files.

triangulation, an Octave code which carries out various operations on order 3 ("linear") or order 6 ("quadratic") triangulations.

triangulation_corner, an Octave code which patches triangulations so that no triangle has two sides on the boundary.

triangulation_delaunay_discrepancy, an Octave code which measures the amount by which a triangulation fails the local Delaunay test;

triangulation_histogram, an Octave code which computes histograms of data over a triangulation.

triangulation_mask, an Octave code which takes an existing triangulation and deletes triangles and their corresponding nodes as requested by the user.

triangulation_order3, a directory which describes the format for the node and element files describing an order 3 triangulation.

triangulation_order6_contour, an Octave code which can display a contour plot of scalar data defined on a triangulation of order 6.

triangulation_orient, an Octave code which reads data defining a triangulation, makes sure that every triangle has positive orientation, and if not, writes a corrected triangle file.

triangulation_quad, an Octave code which estimates the integral of a function over a triangulated region.

triangulation_refine, an Octave code which reads data defining a triangulation, replaces each triangle by four congruent smaller ones, and writes the new triangulation information to a file.

Source Code:

• triangulation_order3_contour.m, the routine for creating the contour plot;