/* -*- mode: C -*-  */
/*
   IGraph library.
   Copyright (C) 2007-2012  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>

int print_vector(const igraph_vector_t *v) {
    long int i, n = igraph_vector_size(v);
    for (i = 0; i < n; i++) {
        printf("%.2g", (double)VECTOR(*v)[i]);
        if (i != n - 1) {
            printf(" ");
        }
    }
    printf("\n");
    return 0;
}

int print_matrix(const igraph_matrix_t *m) {
    long int i, j, nrow = igraph_matrix_nrow(m), ncol = igraph_matrix_ncol(m);
    for (i = 0; i < nrow; i++) {
        for (j = 0; j < ncol; j++) {
            printf("%.2g", (double)MATRIX(*m, i, j));
            if (j != ncol - 1) {
                printf(" ");
            }
        }
        printf("\n");
    }
    return 0;
}

int main() {

    igraph_t g;
    igraph_matrix_t merges;
    igraph_vector_t membership;
    igraph_vector_t x;
    igraph_arpack_options_t options;

    /* Zachary Karate club */
    igraph_small(&g, 0, IGRAPH_UNDIRECTED,
                 0,  1,  0,  2,  0,  3,  0,  4,  0,  5,
                 0,  6,  0,  7,  0,  8,  0, 10,  0, 11,
                 0, 12,  0, 13,  0, 17,  0, 19,  0, 21,
                 0, 31,  1,  2,  1,  3,  1,  7,  1, 13,
                 1, 17,  1, 19,  1, 21,  1, 30,  2,  3,
                 2,  7,  2,  8,  2,  9,  2, 13,  2, 27,
                 2, 28,  2, 32,  3,  7,  3, 12,  3, 13,
                 4,  6,  4, 10,  5,  6,  5, 10,  5, 16,
                 6, 16,  8, 30,  8, 32,  8, 33,  9, 33,
                 13, 33, 14, 32, 14, 33, 15, 32, 15, 33,
                 18, 32, 18, 33, 19, 33, 20, 32, 20, 33,
                 22, 32, 22, 33, 23, 25, 23, 27, 23, 29,
                 23, 32, 23, 33, 24, 25, 24, 27, 24, 31,
                 25, 31, 26, 29, 26, 33, 27, 33, 28, 31,
                 28, 33, 29, 32, 29, 33, 30, 32, 30, 33,
                 31, 32, 31, 33, 32, 33,
                 -1);

    igraph_matrix_init(&merges, 0, 0);
    igraph_vector_init(&membership, 0);
    igraph_vector_init(&x, 0);
    igraph_arpack_options_init(&options);

    igraph_community_leading_eigenvector(&g, /*weights=*/ 0, &merges,
                                         &membership, 1,
                                         &options, /*modularity=*/ 0,
                                         /*start=*/ 0, /*eigenvalues=*/ 0,
                                         /*eigenvectors=*/ 0, /*history=*/ 0,
                                         /*callback=*/ 0,
                                         /*callback_extra=*/ 0);

    print_matrix(&merges);
    print_vector(&membership);

    printf("\n");

    /* Make all the steps */
    igraph_community_leading_eigenvector(&g, /*weights=*/ 0, &merges,
                                         &membership, igraph_vcount(&g),
                                         &options, /*modularity=*/ 0,
                                         /*start=*/ 0, /*eigenvalues=*/ 0,
                                         /*eigenvectors=*/ 0, /*history=*/ 0,
                                         /*callback=*/ 0,
                                         /*callback_extra=*/ 0);

    print_matrix(&merges);
    print_vector(&membership);

    igraph_vector_destroy(&x);
    igraph_vector_destroy(&membership);
    igraph_matrix_destroy(&merges);
    igraph_destroy(&g);

    return 0;
}