\\ 0 = conductor, 1 = tail, 2 = head, 3 = empty
wireworldStep(M)={
	my(sz=matsize(M),t);
	matrix(sz[1],sz[2],x,y,
		t=M[x,y];
		if(t,
			[0,1,3][t]
		,
			t=sum(i=max(x-1,1),min(x+1,sz[1]),
				sum(j=max(y-1,1),min(y+1,sz[2]),
					M[i,j]==2
				)
			);
			if(t==1|t==2,2,3)
		)
	)
};
animate(M)={
	while(1,display(M=wireworldStep(M)))
};
display(M)={
	my(sz=matsize(M),t);
	for(i=1,sz[1],
		for(j=1,sz[2],
			t=M[i,j];
			print1([".","t","H"," "][t+1])
		);
		print
	)
};
animate(read("wireworld.gp"))