用Matlab绘制彩虹

hold on;

i=-1.1:.1:1.1
y=abs（i）;
p=plot（iy）;
set（p‘Color‘‘white‘‘LineWidth‘8）;

offset=0.04;

r=1;
x=linspace（-rr1000）;
y1=sqrt（power（r2）-power（x2））;
p=plot（xy1）;
set（p‘Color‘‘red‘‘LineWidth‘8）;

r=r-offset;
x=linspace（-rr1000）;
y1=sqrt（power（r2）-power（x2））;
p=plot（xy1）;
set（p‘Color‘‘yellow‘‘LineWidth‘8）;

r=r-offset;
x=linspace（-rr1000）;
y1=sqrt（power（r2）-power（x2））;
p=plot（xy1）;