Forest Fires         
             by            
       Michael Creutz      
   creutz@wind.phy.bnl.gov         

(modified by JAR for simulation of spread of a fire line)

Usage:
	xburn initial_fraction_trees  [block_size]

 This program simulates a forest fire.
 
 On each site of a lattice is either 
 nothing, a tree, or a fire.
 In one time step a fire spreads to 
 adjacent trees and leaves an
 empty space.  Initially, trees randomly 
 fill the lattice to a fraction
 given as the first command-line
 parameter.  To start the simulation
 a vertical line of fires is set.
 The lattice wraps (is periodic)
 in both dimensions.  The simulation 
 halts when all fires die out.

 The block size command line parameter
 governs the size of the picture
 of the lattice; the default is 1;
 allowed values are {1,2,4}.  This
 parameter is optional. (The
 initial fraction trees must be
 given on the command line.)

This program is freely distributable.