Question

我正在尝试实现为C中的2D数组的每一行计算一维FFT。这是我的代码（这里的m和n分别是行数和矩阵的列数）：

int howmany;
int i;
int idist = 1;
int inembed;
int istride;
int j;
int m;
int n;
int odist = 1;
int onembed;
int ostride;
int rank = 1;

fftw_complex *in;
fftw_complex *out;

fftw_plan plan_forward;

m = atoi(argv[1]);
n = atoi(argv[2]);

howmany = m;
istride = n;
ostride = n;
inembed = n;
onembed = n;

in = fftw_malloc ( sizeof ( fftw_complex ) * m * n );
out = fftw_malloc ( sizeof ( fftw_complex ) * m * n );

for ( i = 0; i < ( m * n ); i++ )
{
    in[i][0] = m * n - i - 1 ;
    in[i][1] = 0 ;
}

printf("Print Initial Data: \n");
for ( i = 0 ; i < m ; i ++)
{
    for ( j = 0; j < n; j++ )
    {
        printf ( "  %12f\t", in[j + i * n][0]);
    }
    printf("\n");
}

plan_forward = fftw_plan_many_dft(rank, &n, howmany,
        in, &inembed,
        istride, idist,
        out, &onembed,
        ostride, odist,
        FFTW_FORWARD, FFTW_ESTIMATE);

fftw_execute ( plan_forward );

printf("Print Result FFT:\n");
for ( i = 0 ; i < m ; i ++)
{
    for ( j = 0; j < n; j++ )
    {
        printf ( "  %4d  %12f  %12f\n", i, out[j + i * n][0], out[j + i * n][1] );
    }
    printf("\n");
}

fftw_destroy_plan ( plan_forward );

fftw_free ( out );
fftw_free ( in );

以下是4 x 4 2D阵列的结果：

Print Initial Data: 
 15.000000       14.000000       13.000000       12.000000  
 11.000000       10.000000        9.000000        8.000000  
  7.000000        6.000000        5.000000        4.000000  
  3.000000        2.000000        1.000000        0.000000  
Print Result FFT:
 0     36.000000      0.000000
 0     32.000000      0.000000
 0     28.000000      0.000000
 0     24.000000      0.000000

 1      8.000000     -8.000000
 1      8.000000     -8.000000
 1      8.000000     -8.000000
 1      8.000000     -8.000000

 2      8.000000      0.000000
 2      8.000000      0.000000
 2      8.000000      0.000000
 2      8.000000      0.000000

 3      8.000000      8.000000
 3      8.000000      8.000000
 3      8.000000      8.000000
 3      8.000000      8.000000

任何人都可以告诉我为什么我的错误结果？我可能以错误的方式调用fftw_plan fftw_plan_many_dft，但我看不到它。

FFTW - 用于C中2D阵列的1D FFT

0 个答案: