warning off;
nvec = [2,5,10];
x = linspace(-pi/2,pi/2,100);
gx = meshgrid(x,x);
gy = meshgrid(x,x)';
g  = gy-gx;

for k = 1:length(nvec)
    subplot(3,3,k)
    z = sin((nvec(k)+.5).*g)./(2*pi*sin(g/2));
    d = (2*nvec(k)+1)/(2*pi);
    for j=1:100
       z(j,j) = d;
    end
    mesh(x,x,z);
    title(['Darstellung des Dirichlet-Kerns D_{' num2str(nvec(k)) ...
        '}'])
end

for k = 1:length(nvec)
    subplot(3,3,3+k)
    z = ((sin(nvec(k)*.5.*g)).^2)./(nvec(k)*2*pi*(sin(g/2)).^2);
    d = nvec(k)/(2*pi);
    for j=1:100
       z(j,j) = d;
    end
    mesh(x,x,z);
    title(['Darstellung des Fejer-Kerns F_{' num2str(nvec(k)) ...
        '}'])
end

for k = 1:length(nvec)
    subplot(3,3,6+k)
    z = (sin(nvec(k)*.5*g)./(sin(g/2))).^4;
    d = nvec(k)^4;
    for j=1:100
       z(j,j) = d;
    end
    mesh(x,x,z);
    title(['Darstellung des Jackson-Kerns J_{' num2str(nvec(k)) ...
        '}'])
end