代入欧拉公式 e te e cost= 2 SInt= 2i f(x)=2+∑( acos nTuC +b, sin-) nTcr ib nUX nTox +∑ e fe 2 2 2 a-ib nT℃ +ib nTc 2 +∑ H-=1 2 2代入欧拉公式 , 2 cos it it e e t − + = , 2 sin i e e t it −it − = ( cos sin ) 2 ( ) 1 0 l n x b l n x a a f x n n n  +  = +  =   =  −   −                − −         = + + 1 0 2 n 2 2 l n x i l n x i l n n x i l n x i n e e ib e e a a   =  −        + + − = + 1 0 2 n 2 2 l n x i l n n n x i n n e a ib e a a ib