网上找的纯C实现的FFT,与matlab计算结果完全一样

直接上代码了

fft.c

#include "math.h"
#include "fft.h"
//精度0.0001弧度
void conjugate_complex(int n,complex in[],complex out[])
{
  int i = 0;
  for(i=0;i<n;i++)
  {
    out[i].imag = -in[i].imag;
    out[i].real = in[i].real;
  }	
}
void c_abs(complex f[],float out[],int n)
{
  int i = 0;
  float t;
  for(i=0;i<n;i++)
  {
    t = f[i].real * f[i].real + f[i].imag * f[i].imag;
    out[i] = sqrt(t);
  }	
}
void c_plus(complex a,complex b,complex *c)
{
  c->real = a.real + b.real;
  c->imag = a.imag + b.imag;
}
void c_sub(complex a,complex b,complex *c)
{
  c->real = a.real - b.real;
  c->imag = a.imag - b.imag;	
}
void c_mul(complex a,complex b,complex *c)
{
  c->real = a.real * b.real - a.imag * b.imag;
  c->imag = a.real * b.imag + a.imag * b.real;	
}
void c_div(complex a,complex b,complex *c)
{
  c->real = (a.real * b.real + a.imag * b.imag)/(b.real * b.real +b.imag * b.imag);
  c->imag = (a.imag * b.real - a.real * b.imag)/(b.real * b.real +b.imag * b.imag);
}
#define SWAP(a,b)  tempr=(a);(a)=(b);(b)=tempr
void Wn_i(int n,int i,complex *Wn,char flag)
{
  Wn->real = cos(2*PI*i/n);
  if(flag == 1)
  Wn->imag = -sin(2*PI*i/n);
  else if(flag == 0)
  Wn->imag = -sin(2*PI*i/n);