说明：  IDL傅里叶编程 傅里叶函数是指任何一个函数F(x)都能用正弦函数或者余弦函数及他们的组合关系式表示出来。
(The IDL Fourier programming the Fourier function refers to a function F (x) of sine function or cosine function can be used and their combination relationship represented.)