Supplement 1. A C program implementing the algorithm for generating landscapes with spatially structured heterogeneities.

File List
2x1gen.c --
c source code

Description
This file is the source code for
a program (written in the C programming language) that generates rectangular
arrays representing landscapes with two habitat types. The habitat types have
local spatial clustering, as described in the "Landscapes" section
of the paper, and as shown in Fig. 1.

The landscape can be output in
a couple of different formats. The default behavior is to output an ASCII
text file (with a small header) containing a picture of the landscape, with
the characters `.' and `X' representing the two habitat types. This is probably
most useful when working with landscapes less than approximately 70 x 70 sites.
The program can also output the landscape in a raw binary format (with a small
header). Finally, it is also capable of storing the landscape in a PGM (Portable
Graymap) file. There is a large collection of free utilities written by Jef
Poskanzer which manipulate files of this format and convert them to many other
image formats (such as GIF); these utilities are included with many distributions
of Linux, or you can download them from the ACME
Laboratories pbmplus page.

You will need some kind of standard
ANSI C compiler to compile the code. There are comments at the beginning of
the program indicating portability concerns. In particular, the program was
developed using "gcc" under the Linux operating system. If you are
using a different environment, the calls to the random number generator may
need to be modified.