fft.h

国外网站找到的

#include <math.h>
#include <stdio.h>
#include <stdlib.h>

typedef double real64;      /* 64 bit floating point */
typedef float  real32;      /* 32 bit fixed point */

typedef struct complex
{ 
  real32 real;
  real32 imag;
} complex ;

#define TWICEPI 6.28318530717959