axis([0 20 -1 1])
x=0:0.01:20;
for k = 0:2
    		y= besselh(1,k,x);
    		hold on;   
    		if k == 0
    		    plot(x,y,'k');
    		end
   		if k == 1
   		     plot(x,y,'k:');
   		end
    		if k == 2
     		   plot(x,y,'k--');
    		end
end
