x0 = 0 ;
y0 = 1 ;
X  = 2 ;
N  = 30 ;
[x,y]=test_1_taylor(x0,y0,X,N) ;
hold off ;
plot(x,y,'.-b');
hold on ;
x = [x0:(X-x0)/200:X];
plot(x,test_1_esatta(x),'-r');
legend('approssimata','esatta');
