% derivata di x^5

h=1.e-7;
x0=[10 100 1000 10000];

fpv = 5*x0.^4;
fp1 = ((x0+h).^5-x0.^5)/h;
fp2 = (x0.^4 + x0.^3.*(x0+h) + x0.^2.*(x0+h).^2+x0.*(x0+h).^3+(x0+h).^4);
ea(1,:) = abs(fpv-fp1);
er(1,:) = ea(1,:)./abs(fpv);
ea(2,:) = abs(fpv-fp2);
er(2,:) = ea(2,:)./abs(fpv);