命令行下面的使用方式：

 Plot two curves, one is data, the second a model. Allow the selection tool (the lasso) to only see the data.

x = 0:.01:1;
y = exp(x);
ydata = y + randn(size(y))/2;

h1 = plot(x,y,'r-');
hold on
h2 = plot(x,ydata,'o');
[pind,xs,ys] = selectdata('sel','lasso','ignore',h1)