
function esercizio1

f=@(x) 1./(1+x.^2);
x=linspace(-5,5,11);
y=feval(f,x);

c = polnewton (x,y);
xstar=linspace(-5,5,201);
fxstar=feval(f,xstar);
pxstar=horner(x,c,xstar);

plot(xstar,fxstar,'k-',xstar,pxstar,'r--',x,y,'ro');