f(x) = sinxdivided (0,1) into n equal intervals with width 1/n0/n ,1/n,2/n,.,(n-1)/n这是定积分的定义(1/n){ sin(0/1)+ sin(1/n)+ sin(2/n)+...+sin[(n-1)/n] }= ∫(0->1) sinx dx