C語言實現FFT算法
fft1d.c和fft1d.h見
https://download.csdn.net/download/weixin_43216875/12009644
1. fft1d.h
#ifndef FFT1D_H
#define FFT1D_H
#include "math.h"
#define PI 3.1415926535897932384626433832795028841971
typedef struct complex //複數類型
{
float real; //實部
float imag; //虛部
}complex;
void conjugate_complex(int n,complex in[],complex out[]);
void c_plus(complex a,complex b,complex *c);//複數加
void c_mul(complex a,complex b,complex *c) ;//複數乘
void c_sub(complex a,complex b,complex *c); //複數減法
void c_div(complex a,complex b,complex *c); //複數除法
void fft(int N,complex f[]);//傅立葉變換 輸出也存在數組f中
void ifft(int N,complex f[]); // 傅里葉逆變換
void c_abs(complex f[],float out[],int n);//複數數組取模
#endif // FFT1D_H
2. main函數
#include <iostream>
using namespace std;
#include "fft1d.h"
#define N 4 //N取值爲2^n
int main()
{
complex a[N];
float b[N];
for(int i=0;i<N;i++)
{
a[i].real = i+1;
a[i].imag = 0;
}
cout << "data:" << endl;
for(int i=0;i<N;i++)
cout << a[i].real << endl;
fft(N,a);
cout << endl << "fft:" << endl;
for(int i=0;i<N;i++)
cout << a[i].real << "+" << a[i].imag << "j" << endl;
ifft(N,a);
c_abs(a,b,N);
cout << endl << "ifft:" << endl;
for(int i=0;i<N;i++)
cout << b[i] << endl;
return 0;
}