matlab概率密度分布圖，在[-1.1]分成十段，我的編程錯在哪，幫忙看下

>>?x=[-0.9?-0.8?-0.6?-0.4?-0.8?-0.7?0.2?0.5?0.6?0.1];

y=linspace(-1,1,10);

yy=hist(X,y);

yy=yy/length(X);

bar(y,yy);

axis([-0.4?1.6?0?1])?

set(gca,'ytick',[-0.4?-0.2?0?0.2...1.6])