同理可得 g[cos kt]= cosktes'dt (ek+e k)edt 1(c+。(S-k)dt+ (s+jk) dt 2 ,(s-jk)|+∞ (s+jk)t 2s-ik S+ik k s+jk tk15 同理可得 2 2 0 ( j ) 0 ( j ) 0 ( j ) 0 ( j ) 0 j j 0 j 1 j 1 2 1 j 1 j 1 2 1 e d e d 2 1 (e e ) e d 2 1 [cos ] cos e d s k s s k s k e s k e s k t t t k t k t t s k t s k t s k t s k t kt kt s t s t +  =      + + - =       + - + - - =       = + = + = + - + + - - + - + + - - + - - + -    L 