% Runge phenomenon
function interp_runge
   	numnodes = 3
	x = linspace(-1,1,numnodes);
	y = runge(x);
	plot(x,y,'k*'); hold on;

	n = numel(x);
	c = newtdd(x,y,n);
	
	xx = linspace(x(1),x(n),400);
	plot(xx,runge(xx),'b');
	yy = nest(n-1,c,xx,x);
	plot(xx,yy,'r'); 
	title('Runge function (blue) and poly interpolant (red)');
	hold off;
end

function y = runge(x)
	y = 1./(1+12*x.^2);
end