view tests/pointset_test/genpoints2.c @ 620:70fc1a504138

Okay, I think my python bindings have reached the border of useful, so in the svn they go.

The bindings currently allow for adb create and open, status and the setting of the l2norm and power flags.

Note that these are the direct c bindings, when it's done there will be OO dressing on top for standard entry.
Also, even though I don't use numpy yet, the include file is brought in, so the module won't build if you don't have numpy in an importable place.

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <math.h>
#include <stdlib.h>
#include <stdio.h>

double randn();
double randbl();

/* genpoints count radius^2 */
int main(int argc, char *argv[]) {
  if (argc < 3) {
    fprintf(stderr, "usage: %s count radius^2 [dim]\n", argv[0]);
    exit(1);
  }
  long int count = strtol(argv[1], NULL, 0);
  double rsquared = strtod(argv[2], NULL);
  long int dim = 3;
  if(argc > 3)
    dim = strtol(argv[3], NULL, 0);
  
  // Generate *count* Gaussian Random vectors in R^*dim*
  // sitting on the *rdashed*-sphere

  srandom(time(NULL));

  int i,j;
  for (i = 0; i < count + 1; i++) {
    // Normed Gaussian random vectors are distributed uniformly on unit sphere
    double* coords = malloc(dim * sizeof(double));
    double nmsq = 0.0;

    for (j = 0; j < dim; j++){
      if(i < count)
	coords[j] = randn();
      else
	coords[j] = 0.0;
      nmsq += coords[j]*coords[j];
    }

    double nm2 = 0.0;
    if(i < count){
      nm2 = sqrt(rsquared/nmsq);
      // Place on rdash-sphere
      for (j = 0; j < dim; j++)
	coords[j] *= nm2;
    }
    // Translate to (0,0,...,1)
    coords[dim-1]+=1.0; 

    // Compute distance to (0,0,...,1)
    nmsq = 0.0;
    for (j = 0; j < dim-1; j++){
      nmsq += coords[j]*coords[j];
    }
    // Save last value to distance calulcation to query(0,0,...,1)
    double nth = coords[dim-1];
    // Output to ASCII terminal
    printf("(");
    for(j = 0; j < dim; j++)
      printf("%8.3f ", coords[j]);
    printf(") d = %8.3f\n", sqrt(nmsq + (nth-1)*(nth-1)));
    

    // Save single feature vector
    char name[40];
    if(i < count)
      snprintf(name, 39, i<10?"testfeature0%d":"testfeature%d", i);
    else
      snprintf(name, 39, "queryfeature");
    /* assumes $PWD is right */
    int fd = open(name, O_CREAT|O_TRUNC|O_WRONLY, S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH);

    write(fd, &dim, sizeof(int));
    for(j = 0; j < dim; j++)
      write(fd, coords + j, sizeof(double));
    close(fd);

    free(coords);
  }
  exit(0);
}

// Genereate U[0,1]
double randbl(){
  return (   (double)rand() / ((double)(RAND_MAX)+(double)(1)) );
}

// Generate z ~ N(0,1)
double randn(){
// Box-Muller
  double x1, x2;
  do{
    x1 = randbl();
  } while (x1 == 0); // cannot take log of 0
  x2 = randbl();
  double z = sqrt(-2.0 * log(x1)) * cos(2.0 * M_PI * x2);
  return z;
}