周期函数/(am)=A+∑AmSm(kO+9) k=1 km sin( kot+pu =Akm,(sin kat cos pr+cos kosin k) = Akm cos sin kat+ Akm sin k cos kat -B sin kot+c cos kot f(0=4+∑ Bkmn sin ka+ k=1 As km cos kat9    =  = = + + 1 1 0 ( ) sin cos k km k km f w t A B kw t C kw t 周期函数 ( ) ( ) 1 0 k k km f wt = A +A Sin kw t +  = B k t C k t A k t A k t A k t k t A k t km km km k km k km k k km k = + = + = + + w w  w  w w  w  w  sin cos cos sin sin cos (sin cos cos sin ) sin( )