這函數的傅立葉展開式為

    

         

             

             

                                                    

              

                                                  

                                

                                         

                                          得證                                    

             

 

       n=1時

傅立葉展開式動畫

       n=2時

傅立葉展開式動畫

 

        n=3時

傅立葉展開式動畫