function integr = integrale_formula( f , ab , n , formula ) n = 2 * floor( n / 2 ) ; x = linspace( ab(1) , ab(2) , n+1 ) ; dx = x(2) - x(1) ; f_x = f( x ) ; switch formula case 1 % Trapezi estremi = f_x(1) + f_x(end) ; interni = 2 * sum( f_x(2:end-1) ) ; integr = (dx/2) * ( estremi + interni ) ; case 2 % Simpson estremi = f_x(1) + f_x(end) ; interni_pari = 4 * sum( f_x(2:2:end-1) ) ; interni_dispari = 2 * sum( f_x(3:2:end-2) ) ; integr = (dx/3) * ( estremi + interni_pari + interni_dispari ) ; end end