
function chebs

theta=linspace(0,pi,1000);
thetac=linspace(0,pi,7);

clf;

axis off;
axis equal;
hold on;

x=cos(theta); y=sin(theta);
plot(x,y,'k-','LineWidth',2,...
                       'MarkerEdgeColor','k',...
                       'MarkerFaceColor','k',...
                       'MarkerSize',2);


                   
x=cos(thetac); y=sin(thetac);
plot(x,y,'ro','LineWidth',8,...
                       'MarkerEdgeColor','r',...
                       'MarkerFaceColor','r',...
                       'MarkerSize',8);     


                   
 for ii=1:length(thetac)
    plot([cos(thetac(ii)) cos(thetac(ii))],[0 sin(thetac(ii))],'r--','LineWidth',2,...
                       'MarkerEdgeColor','r',...
                       'MarkerFaceColor','r',...
                       'MarkerSize',2);  
                       plot([0 cos(thetac(ii))],[0 sin(thetac(ii))],'r--','LineWidth',2,...
                       'MarkerEdgeColor','r',...
                       'MarkerFaceColor','r',...
                       'MarkerSize',2);
 end
 
  xx=[-1 1]; yy=[0 0];
plot(xx,yy,'k-','LineWidth',2,...
                       'MarkerEdgeColor','k',...
                       'MarkerFaceColor','k',...
                       'MarkerSize',2); 
                   
                   
                   x=cos(thetac); y=zeros(size((thetac)));
plot(x,y,'bo','LineWidth',8,...
                       'MarkerEdgeColor','b',...
                       'MarkerFaceColor','b',...
                       'MarkerSize',8); 
hold off;