充分理解傅立叶变换，直接根据傅立叶积分公式编写，并显示单边，双边谱，对于理解单双边频谱有一定帮助。本程序通过函数与调用来呈现。-Fully understand the Fourier transform, Fourier integral formula directly in accordance with the preparation, and display the unilateral, bilateral spectrum, the spectrum for the understanding of a certain single bilateral help. This procedure with the call to a function.