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/* -*- mode: C -*- */
/*
IGraph library.
Copyright (C) 2006-2012 Gabor Csardi <csardi.gabor@gmail.com>
334 Harvard st, 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>
#include <math.h>
#include <stdlib.h>
#define sqr(x) ((x)*(x))
int main() {
igraph_t g;
igraph_matrix_t coords, dist_mat;
igraph_arpack_options_t options;
int i, j;
srand(time(0));
igraph_arpack_options_init(&options);
igraph_tree(&g, 10, 2, IGRAPH_TREE_UNDIRECTED);
igraph_matrix_init(&coords, 0, 0);
igraph_layout_mds(&g, &coords, 0, 2, &options);
if (MATRIX(coords, 0, 0) > 0) {
for (i = 0; i < igraph_matrix_nrow(&coords); i++)
MATRIX(coords, i, 0) *= -1;
}
if (MATRIX(coords, 0, 1) < 0) {
for (i = 0; i < igraph_matrix_nrow(&coords); i++)
MATRIX(coords, i, 1) *= -1;
}
igraph_matrix_print(&coords);
igraph_matrix_destroy(&coords);
igraph_destroy(&g);
igraph_full(&g, 8, IGRAPH_UNDIRECTED, 0);
igraph_matrix_init(&coords, 8, 2);
igraph_matrix_init(&dist_mat, 8, 8);
for (i = 0; i < 8; i++)
for (j = 0; j < 2; j++)
MATRIX(coords, i, j) = rand() % 1000;
for (i = 0; i < 8; i++)
for (j = i+1; j < 8; j++) {
double dist_sq = 0.0;
dist_sq += sqr(MATRIX(coords, i, 0)-MATRIX(coords, j, 0));
dist_sq += sqr(MATRIX(coords, i, 1)-MATRIX(coords, j, 1));
MATRIX(dist_mat, i, j) = sqrt(dist_sq);
MATRIX(dist_mat, j, i) = sqrt(dist_sq);
}
igraph_layout_mds(&g, &coords, &dist_mat, 2, &options);
for (i = 0; i < 8; i++)
for (j = i+1; j < 8; j++) {
double dist_sq = 0.0;
dist_sq += sqr(MATRIX(coords, i, 0)-MATRIX(coords, j, 0));
dist_sq += sqr(MATRIX(coords, i, 1)-MATRIX(coords, j, 1));
if (fabs(sqrt(dist_sq) - MATRIX(dist_mat, i, j)) > 1e-2) {
printf("dist(%d,%d) should be %.4f, but it is %.4f\n",
i, j, MATRIX(dist_mat, i, j), sqrt(dist_sq));
return 1;
}
}
igraph_matrix_destroy(&dist_mat);
igraph_matrix_destroy(&coords);
igraph_destroy(&g);
return 0;
}
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