在VB中实现对文本文档中数据的傅里叶变换。并出现变换后的波形-The useful functions are:

　FourierTransform() performs a Fast Fourier Transform on an pair of

　 Double arrays-- one real, one imaginary.　Don t want/need

　 imaginary numbers?　Just use an array of 0s.　This function can

　 also do inverse FFTs.

　FrequencyOfIndex() can tell you what actual frequency a given index

　 corresponds to.

　CalcFrequency() transforms a single frequency.