text: /* -*- mode: C -*-  */
  /* vim:set ts=2 sts=2 sw=2 et: */
  /* 
     IGraph library.
     Copyright (C) 2006-2012  Gabor Csardi <csardi.gabor@gmail.com>
     334 Harvard street, Cambridge, MA 02139 USA
     
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 2 of the License, or
     (at your option) any later version.
     
     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
     
     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc.,  51 Franklin Street, Fifth Floor, Boston, MA 
     02110-1301 USA
  
  */
  
  #include <igraph.h>
  
  void show_results(igraph_t *g, igraph_vector_t *membership, igraph_matrix_t *memberships, igraph_vector_t *modularity, FILE* f) {
    long int i, j, no_of_nodes = igraph_vcount(g);
  
    j=igraph_vector_which_max(modularity);
    for (i=0; i<igraph_vector_size(membership); i++) {
      if (VECTOR(*membership)[i] != MATRIX(*memberships, j, i)) {
        fprintf(f, "WARNING: best membership vector element %li does not match the best one in the membership matrix\n", i);
      }
    }
  
    fprintf(f, "Modularities:\n");
    igraph_vector_print(modularity);
  
    for (i=0; i < igraph_matrix_nrow(memberships); i++) {
      for (j=0; j < no_of_nodes; j++) {
        fprintf(f, "%ld ", (long int)MATRIX(*memberships, i, j));
      }
      fprintf(f, "\n");
    }
  
    fprintf(f, "\n");
  }
  
  int main() {
    igraph_t g;
    igraph_vector_t modularity, membership, edges;
    igraph_matrix_t memberships;
    int i, j, k;
  
    igraph_vector_init(&modularity,0);
    igraph_vector_init(&membership,0);
    igraph_matrix_init(&memberships,0,0);
  
    /* Unweighted test graph from the paper of Blondel et al */
    igraph_small(&g, 16, IGRAPH_UNDIRECTED,
        0, 2, 0, 3, 0, 4, 0, 5,
        1, 2, 1, 4, 1, 7,
        2, 4, 2, 5, 2, 6,
        3, 7,
        4, 10,
        5, 7, 5, 11,
        6, 7, 6, 11,
        8, 9, 8, 10, 8, 11, 8, 14, 8, 15,
        9, 12, 9, 14,
        10, 11, 10, 12, 10, 13, 10, 14,
        11, 13,
        -1);
    igraph_community_multilevel(&g, 0, &membership, &memberships, &modularity);
    show_results(&g, &membership, &memberships, &modularity, stdout);
    igraph_destroy(&g);
  
    /* Ring of 30 cliques */
    igraph_vector_init(&edges,0);
    for (i = 0; i < 30; i++) {
      for (j = 0; j < 5; j++) {
        for (k = j+1; k < 5; k++) {
          igraph_vector_push_back(&edges, i*5+j);
          igraph_vector_push_back(&edges, i*5+k);
        }
      }
    }
    for (i = 0; i < 30; i++) {
      igraph_vector_push_back(&edges, i*5 % 150);
      igraph_vector_push_back(&edges, (i*5+6) % 150);
    }
    igraph_create(&g, &edges, 150, 0);
    igraph_community_multilevel(&g, 0, &membership, &memberships, &modularity);
    show_results(&g, &membership, &memberships, &modularity, stdout);
    igraph_destroy(&g);
  
    igraph_vector_destroy(&modularity);
    igraph_vector_destroy(&membership);
    igraph_vector_destroy(&edges);
    igraph_matrix_destroy(&memberships);
  
  #ifdef __APPLE__
    return 0;
  #else
    return 77;
  #endif
  }
  