FFT算法用标准C++实现，具有实数FFT变换函数、复数FFT变化函数，以及频谱分析功能。并给出了该算法在C++Builder环境下测试代码。-This file contains a few FFT routines, including a real-FFT routine that is almost twice as fast as a normal complex FFT, and a power spectrum routine when you know you d