离散傅里叶变换，逆变换（c语言）

离散傅⾥叶变换，逆变换（c语⾔）#include <stdio.h>
#include <math.h>
#include "dfc.h"
#define pi 3.1415926
complex complexadd(complex a, complex b){ //复数加
complex rt;
rt.re = a.re + b.re;
rt.im = a.im + b.im;
return rt;
}
complex complexMult(complex a, complex b){ //复数乘
complex rt;
rt.re = a.re*b.re-a.im*b.im;
rt.im = a.im*b.re+a.re*b.im;
return rt;
}
//离散傅⾥叶变换
void dft(complex X[], complex x[], int N){ //X[]标识变换后频域，x[]为时域采样信号，下同
complex temp;
int k, n;
for (int k = 0; k < N; k++)
{
X[k].re = 0;
X[k].im = 0;
for (int n = 0; n < N; n++)
{
temp.re = (float)cos(2*pi*k*n/N);
temp.im = -(float)sin(2*pi*k*n/N);
X[k] = complexadd(X[k], complexMult(x[n],temp));
}
}
}
//离散傅⾥叶逆变换
void idft(complex X[], complex x[], int N){
complex temp;
int k, n;
for (int k = 0; k < N; k++)
{
x[k].re = 0;
x[k].im = 0;
for (int n = 0; n < N; n++)
{
temp.re = (float)cos(2*pi*k*n/N);
temp.im = (float)sin(2*pi*k*n/N);
x[k] = complexadd(x[k], complexMult(X[n],temp));
}
x[k].re /= N;
x[k].im /= N;
}
}
主程序：
#include <stdio.h>
#include "src/dfc.h"
#define N 10
int main(){
complex samples[N], X[N],x[N]; //samples[]⽰例
for (int i = 0; i < N; i++)
{
samples[i].re = i;
samples[i].im = 0;
}
dft(X, samples, N );
printf("DFI:\n");
for (int i = 0; i < N; i++)
{
printf("(%f,%f)\n",X[i].re, X[i].im);
}
//
idft(X, x, N);
printf("IDFI:\n");
for (int i = 0; i < N; i++)
{
printf("(%f,%f)\n",x[i].re, x[i].im); }
}。