f(t)=ao+>(a, cosnQ2t+b, sin nS2t) =A+∑ Am cos(net+qn) n=1 其中: A a.2+b Pn=-arctan其中: ( ) ( cos sin ) 1 0 f t a a n t b n t n n = + n  +   = A A cos(n t ) n n 1 = 0 + mn  +   = 2 n 2 Amn = an + b n n n a b  = −arctan