40 static void construct(
char * file, 
int N, 
int M, 
int Z, fftw_complex *mem)
 
   48   nfft_init_2d(&my_plan,N,N,M/Z);
 
   50   fp=fopen(
"knots.dat",
"r");
 
   54     fscanf(fp,
"%le %le %le",&my_plan.
x[2*j+0],&my_plan.
x[2*j+1],&tmp);
 
   64       my_plan.
f_hat[j] = mem[(z*N*N+N*N*Z/2+j)%(N*N*Z)];
 
   67       nfft_precompute_psi(&my_plan);
 
   73       fprintf(fp,
"%le %le %le %le %le\n",my_plan.
x[2*j+0],my_plan.
x[2*j+1],tmp/Z-0.5,
 
   74               creal(my_plan.
f[j]),cimag(my_plan.
f[j]));
 
   79   nfft_finalize(&my_plan);
 
   86 static void fft(
int N,
int M,
int Z, fftw_complex *mem)
 
   89   plan = fftw_plan_many_dft(1, &Z, N*N,
 
   94                                   FFTW_FORWARD, FFTW_ESTIMATE);
 
   97   fftw_destroy_plan(plan);
 
  104 static void read_data(
int N,
int M,
int Z, fftw_complex *mem)
 
  109   fin=fopen(
"input_f.dat",
"r");
 
  115       fscanf(fin,
"%le ",&real );
 
  116       mem[(z*N*N+N*N*Z/2+i)%(N*N*Z)]=real;
 
  122 int main(
int argc, 
char **argv)
 
  127     printf(
"usage: ./construct_data FILENAME N M Z\n");
 
  131   mem = (fftw_complex*) 
nfft_malloc(
sizeof(fftw_complex) * atoi(argv[2]) * atoi(argv[2]) * atoi(argv[4]));
 
  133   read_data(atoi(argv[2]),atoi(argv[3]),atoi(argv[4]), mem);
 
  135   fft(atoi(argv[2]),atoi(argv[3]),atoi(argv[4]), mem);
 
  137   construct(argv[1],atoi(argv[2]),atoi(argv[3]),atoi(argv[4]), mem);