step(M,p,f)={
	my(m=matsize(M)[1],n=matsize(M)[2]);
	matrix(m,n,i,j,
		if(M[i,j]=="*",
			" "
		,
			if(M[i,j]=="t",
				my(nbr="t");
				for(x=max(1,i-1),min(m,i+1),
					for(y=max(1,j-1),min(n,j+1),
						if(M[x,y]=="*",nbr="*";break(2))
					)
				);
				if(random(1.)<f,"*",nbr)
			,
				if(random(1.)<p,"t"," ")
			)
		)
	)	
};
burn(n,p,f)={
	my(M=matrix(n,n,i,j,if(random(2)," ","t")),N);
	while(1,print(M=step(M,p,f)))
};
burn(5,.1,.03)