3.0 API Reference

construct_data_2d1d.c

#include <stdlib.h>
#include "util.h"
#include "nfft3.h"

void construct(char * file, int N, int M, int Z, fftw_complex *mem)
{
  int j,z;                /* some variables */
  double tmp;             /* a placeholder */
  nfft_plan my_plan;      /* plan for the two dimensional nfft  */
  FILE* fp;
    
  /* initialise my_plan */
  nfft_init_2d(&my_plan,N,N,M/Z);

  fp=fopen("knots.dat","r");
  
  for(j=0;j<my_plan.M_total;j++)
  {
    fscanf(fp,"%le %le %le",&my_plan.x[2*j+0],&my_plan.x[2*j+1],&tmp);
  }
  fclose(fp);

  fp=fopen(file,"w");

  for(z=0;z<Z;z++) {
    tmp = (double) z;
  
    for(j=0;j<N*N;j++)
      my_plan.f_hat[j] = mem[(z*N*N+N*N*Z/2+j)%(N*N*Z)];
    
    if(my_plan.nfft_flags & PRE_PSI)
      nfft_precompute_psi(&my_plan);

    nfft_trafo(&my_plan);

    for(j=0;j<my_plan.M_total;j++)
    {
      fprintf(fp,"%le %le %le %le %le\n",my_plan.x[2*j+0],my_plan.x[2*j+1],tmp/Z-0.5,
              creal(my_plan.f[j]),cimag(my_plan.f[j]));
    }
  }
  fclose(fp);

  nfft_finalize(&my_plan);
}

void fft(int N,int M,int Z, fftw_complex *mem)
{
  fftw_plan plan;
  plan = fftw_plan_many_dft(1, &Z, N*N,
                                  mem, NULL,
                                  N*N, 1,
                                  mem, NULL,
                                  N*N,1 ,
                                  FFTW_FORWARD, FFTW_ESTIMATE);

  fftw_execute(plan); /* execute the fft */
  fftw_destroy_plan(plan);
}

void read_data(int N,int M,int Z, fftw_complex *mem)
{
  int i,z;
  double real;
  FILE* fin;
  fin=fopen("input_f.dat","r");

  for(z=0;z<Z;z++)
  {
    for(i=0;i<N*N;i++)
    {
      fscanf(fin,"%le ",&real );
      mem[(z*N*N+N*N*Z/2+i)%(N*N*Z)]=real;
    }
  }
  fclose(fin);
}

int main(int argc, char **argv)
{ 
  fftw_complex *mem;
  
  if (argc <= 4) {
    printf("usage: ./construct_data FILENAME N M Z\n");
    return 1;
  }

  mem = (fftw_complex*) fftw_malloc(sizeof(fftw_complex) * atoi(argv[2]) * atoi(argv[2]) * atoi(argv[4]));
  
  read_data(atoi(argv[2]),atoi(argv[3]),atoi(argv[4]), mem);

  fft(atoi(argv[2]),atoi(argv[3]),atoi(argv[4]), mem);
 
  construct(argv[1],atoi(argv[2]),atoi(argv[3]),atoi(argv[4]), mem);
  
  fftw_free(mem);
  
  return 1;
}
/* \} */

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