t=-1:0.02:1;
	plot(t,[-4 -3 -2 -1 0 2 3 4]*exp(t),'--k');
	hold on;
	plot(t,exp(t),'-k');
	plot(0,1,'ok','MarkerFaceColor','k');
	axis([-1,1,-4,4]);
					

	t=0:0.01:1;
	plot(t,exp(t),'-k');
	hold on;
	plot(t,2*exp(-t),'--k');
	axis([0 1 0 3]);
					

	t=0:0.01:2*pi;
	plot(sin(t)-0.1,cos(t),'-k');
	hold on;
	plot(sin(t)+0.1,cos(t),'--k');
	axis([-2 2 -2 2]); axis equal;