% Douglas N. Arnold, dna@math.psu.edu, 11/96
% diagram of the Chebyshev points
figure
n=9;
pin=pi/(2*n);
th=linspace(0,pi,100);
set(gca,'aspectratio',[NaN 1],'visible','off',...
  'defaultlinelinewidth',3)

for j=1:2:2*n-1
  patch([0,cos(pin*linspace(j-1,j,20))],[0,sin(pin*linspace(j-1,j,20))],'cyan')
end
for j=2:2:2*n
 patch([0,cos(pin*linspace(j-1,j,20))],[0,sin(pin*linspace(j-1,j,20))],'green')
end

line(cos(th),sin(th))
line([-1,1],[0,0])
line([-1,1],[-.25,-.25],'linewidth',3,'color','yellow')

for j=1:2:2*n-1
  line(cos(pin*j)*[1,1],[sin(pin*j),0],'color','red','linewidth',1)
  line(cos(pin*j),0,'linestyle','.','markersize',30,'color','red')
  line(cos(pin*j),-.25,'linestyle','.','markersize',30,'color','red')
end

text(0,1.25,'Chebyshev points','color','yellow',...
  'horizontalalignment','center','fontname','helvetica',...
  'fontsize',24)