FFTW程序Demo

 #include<stdio.h>
 #include<stdlib.h>
 #include <fftw3.h>
 #include<string.h>
 #include <complex.h>
 int main()
 {

     fftw_complex *in, *out;

     fftw_plan p;

         int N=;
     in = (fftw_complex*) fftw_malloc(sizeof(fftw_complex) * N);

     out = (fftw_complex*) fftw_malloc(sizeof(fftw_complex) * N);

     for(int i=;i<N;i++)
     {
         in[i][]=i+;
         in[i][]=;
     }
     memset(out,,sizeof(out));

     p = fftw_plan_dft_1d(N, in, out, FFTW_FORWARD, FFTW_ESTIMATE);
     fftw_execute(p);
     for(int i=;i<N;i++)
     {
         printf("%f %f i \n",out[i][],out[i][]);
     }
     p = fftw_plan_dft_1d(N, out, in, FFTW_BACKWARD, FFTW_ESTIMATE);
     fftw_execute(p);
 //...
     for(int i=;i<N;i++)
     {
         printf("%f %f i \n",in[i][],in[i][]);
     }

     fftw_destroy_plan(p);

     fftw_free(in);
     fftw_free(out);
     return ;

 }

当n=3的时候结果为：

6.000000 0.000000 i
-1.500000 0.866025 i
-1.500000 -0.866025 i
3.000000 0.000000 i
6.000000 0.000000 i
9.000000 0.000000 i

当n=4的时候结果为：

10.000000 0.000000 i
-2.000000 2.000000 i
-2.000000 0.000000 i
-2.000000 -2.000000 i
4.000000 0.000000 i
8.000000 0.000000 i
12.000000 0.000000 i
16.000000 0.000000 i