x = -pi:.01:pi;
v = [5,10,20,100];

xn = -pi:.01:0;
xp = 0:.01:pi;
zn = -pi-xn;
zp = pi-xp;

for k = 1:length(v)
    subplot(2,2,k)
    plot(xn,zn,'k')
    hold on
    sm = partsum(x,v(k));
    cm = cesaro(x,v(k));
    plot(x,sm,'b',x,cm,'m');
    legend(['B_1'],['S_{' num2str(v(k)) '}[B_1]'],['C_{' num2str(v(k)) '}[B_1]'])
    plot(xp,zp,'k')
end