FFT使用范例。 x=0.5*sin(2*pi*15*t)+2*sin(2*pi*40*t)。采样频率fs=100Hz，分别绘制N=128、1024点幅频图。-FFT usage examples. x = 0.5* sin (2* pi* 15* t)+2* sin (2* pi* 40* t). Sampling frequency fs = 100Hz, were drawn N = 128,1024 point amplitude-frequency diagram.