做一个示例程序：
x = linspace(0,4*pi,100);
y = sin(x);
h = plot(x(1),y(1));
axis([0,4*pi,-1,1])
filename = '动画示例.gif';
f = getframe(gcf);
IM = f.cdata;
[IM,map] = rgb2ind(IM,256);
imwrite(IM,map,filename,'gif', 'Loopcount',inf,'DelayTime',0.2);
for k = 2:length(x)
set(h,'XData',x(1:k),'YData',y(1:k));
drawnow
f = getframe(gcf);
IM = f.cdata;
[IM,map] = rgb2ind(IM,256);
imwrite(IM,map,filename,'gif','WriteMode','append','DelayTime',0.2);
pause(0.2);
end
