**XY** is a data directory which
contains examples of files in the XY format, which are simply lists
of points in the plane.

An XY file has a simple structure. There are three kinds of records:

- COMMENT LINES begin with the character '#' and are ignored;
- BLANK LINES are ignored;
- COORDINATE LINES each contain one pair of X, Y coordinates;

```
# Corners of a triangle
#
0.0 0.0
1.0 0.0
0.0 1.0
```

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

CIRCLE_POINTS, a FORTRAN90 program which computes points equally spaced on a circular arc, and writes them to an XY file;

PLOT_POINTS, a FORTRAN90 program which can make an EPS plot of a set of points in 2D.

XY_DISPLAY, a MATLAB program which reads a XY file containing the coordinates of points in 2D, and displays a plot of the points in a MATLAB graphics window;

XY_DISPLAY_OPENGL, a C++ program which reads XY information defining points in 2D, and displays an image using OpenGL.

XY_IO, a C++ library which reads and writes files in the XY and XYL formats.

XYL, a data directory which contains examples of XYL files, a simple 2D graphics point and line format;

- ASCII
- 2D
- No compression
- 1 image

- arc_10.txt, points on a circular arc, created by CIRCLE_POINTS;
- arc_10.png, a PNG image.
- diamond_02_00009.txt, 9 points, whose Voronoi diagram includes a diamond;
- diamond_02_00009.png, a PNG image.
- dt_10.txt, 10 points; compute the Delaunay triangulation;
- dt_10.png, a PNG image.
- dt_100.txt, 100 points for which the Delaunay triangulation is to be computed;
- dt_100.png, a PNG image.
- graham_10.txt, 10 points for which the convex hull is to be computed;
- graham_10.png, a PNG image.
- graham_19.txt, 19 points for which the convex hull is to be computed;
- graham_19.png, a PNG image.
- grid_49.txt, 49 points in a square grid.
- grid_49.png, a PNG image.
- hexagon_06.txt, vertices of a hexagon, created by CIRCLE_POINTS;
- hexagon_06.png, a PNG image.
- lsup_303.txt, 303 points defining the shape of Lake Superior.
- lsup_303.png, a PNG image.
- mushroom.txt, a mushroom shape.
- mushroom.png, a PNG image.
- pentagon_05.txt, vertices of a pentagon, created by CIRCLE_POINTS;
- pentagon_05.png, a PNG image.
- points_100.txt, 100 points;
- points_100.png, a PNG image.
- repeats_17.txt, 17 points, some repeated;
- repeats_17.png, a PNG image.
- star5.txt, a five-pointed star.
- star5.png, a PNG image.
- star5_sharp.txt, a five pointed star with sharp edges.
- star5_sharp.png, a PNG image.
- tri_12.txt, 12 points;
- tri_12.png, a PNG image.
- tri_18.txt, 18 points;
- tri_18.png, a PNG image.
- uniform_0016.txt, 16 random points in the unit square;
- uniform_0016.png, a PNG image.
- uniform_0025.txt, 25 random points in the unit square;
- uniform_0025.png, a PNG image.
- uniform_0036.txt, 36 random points in the unit square;
- uniform_0036.png, a PNG image.
- uniform_0064.txt, 64 random points in the unit square;
- uniform_0064.png, a PNG image.
- uniform_0100.txt, 100 random points in the unit square;
- uniform_0100.png, a PNG image.
- uniform_0128.txt, 128 random points in the unit square;
- uniform_0128.png, a PNG image.
- uniform_0256.txt, 256 random points in the unit square;
- uniform_0256.png, a PNG image.

You can go up one level to the DATA page.