function [ ] = plot_ball( p )
%plot_ball plots p-norm unit ball in R^2

[x,y] = meshgrid(-1.1:0.01:1.1, -1.1:0.01:1.1);
pnorm = (abs(x).^p + abs(y).^p).^(1/p);
contourf(x,y,pnorm,[1,1]);

end