[a1,a2] = meshgrid(linspace(-1.5,1.5,200));

for p = [1 2 10 .5];
f = (abs(a1).^p+abs(a2).^p).^(1/p);
figure(1);contour(a1,a2,f,[1 1]);axis square;
xlabel('a_1');ylabel('a_2'); grid on
title(['p = ' num2str(p)])
set(gca,'fontsize',18)
pause
end