%CA driver
%
%forest fire
clf
clear all
n=100;
Plightning = .001;
Pgrowth = .0001; 
z=zeros(n,n);
o=ones(n,n);
veg=2*o;
sum=z;
imh = image(cat(3,z,veg==2,z));
set(imh, 'erasemode', 'none')
axis equal
axis tight
% burning -> empty
% green -> burning if one neigbor burning or with prob=f (lightning)
% empty -> green with prob=p (growth)
% veg = {empty=0 burning=1 green=2}


for i=1:50000
%nearby fires?
c=rand(n);%统一的一个随机矩阵 否则执行两次rand会产生不同结果
sum = (veg(1:n,[n 1:n-1])==1) + (veg(1:n,[2:n 1])==1) + ...
(veg([n 1:n-1], 1:n)==1) + (veg([2:n 1],1:n)==1) ;
veg =2*((veg==2)&(c>=Plightning))+((veg==2) &(c<Plightning))...
    +0*(veg==1)+(2*(veg==0)&(c<Pgrowth))+((veg==2)&(sum>0)); %加号之间均为互斥的事件 &与|连接的命题最好带括号


set(imh, 'cdata', cat(3,(veg==1),(veg==2),z) )
drawnow


end