一个matlab画图的代码，画图总是报错，哪位帮忙看看问题出在哪里

[woshigefantong]

本人新手，第一次用matlab画图，现在想在一个图上加一个y=0的虚线。单独测试这条虚线是没有问题的，可是一加到图上就出错。
为题到底出在哪里呢？请帮忙看一下。谢谢
代码如下

红色的代码是画虚线的，单独测试时没有问题的
上面的代码上画一个控制坐标范围在y轴[-0.5,0.5], x轴[0.7,0.9]的图
然后希望在图上加一条y=0的曲线


x=[0.8615,0.8428,0.7852,0.7959,0.7918,0.7199,0.8623,0.7436,0.8691,0.7984,0.7917];
y=[0.29442168063167506,0.19389055483260173,0.24690383487136713,-0.07104419389892005,0.25820812017776185,0.07266947434371361,0.19306162161726803,0.19402755535719096,0.3809557404866936,0.24799455060683467,0.25444282557248116];
figure
scatter(x,y);
axis([0.7 0.9 -0.5 0.5]);
set(gca,'xtick',[0.7 0.75 0.8 0.85 0.9]);
set(gca,'ytick',[-0.5 -0.4 -0.3 ...0.5]);
hold on;
plot([0.7,0.9],[0,0],'--');

[蔡姐]

好像是第2个SET语句有问题，这回能画出虚线了。 x=[0.8615,0.8428,0.7852,0.7959,0.7918,0.7199,0.8623,0.7436,0.8691,0.7984,0.7917]; y=[0.29442168063167506,0.19389055483260173,0.24690383487136713,-0.07104419389892005,0.25820812017776185,0.07266947434371361,0.19306162161726803,0.19402755535719096,0.3809557404866936,0.24799455060683467,0.25444282557248116]; figure(1) scatter(x,y); axis([0.7 0.9 -0.5 0.5]); set(gca,'xtick',[0.7 0.75 0.8 0.85 0.9]); set(gca,'ytick',[-0.5 -0.4 -0.3 0.2 0.5]); hold on; figure(1) plot([0.7,0.9],[0,0],'--'); hold off;