matlab2009中运行 ：x=0:0.01:2*pi; y=sin(x); y2=cos(x); z=[y;y2];

matlab2009中运行 ：x=0:0.01:2*pi; y=sin(x); y2=cos(x); z=[y;y2]; plot(x,z);
出现?Undefined function or method 'setdiff' for input arguments of type 'double'.
Error in ==> clo at 49
kids_to_delete = setdiff(findall(obj,'serializable','on','-depth',1),obj);
Error in ==> cla at 29
clo(ax,extra{:});
Error in ==> newplot>ObserveAxesNextPlot at 134
cla(ax,'reset',hsave);
Error in ==> newplot at 83
ax = ObserveAxesNextPlot(ax,hsave);
小弟初学,请讲浅显