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/* -*- mode: C -*- */
/*
IGraph library.
Copyright (C) 2011-2012 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>
int main() {
int nodes=10;
igraph_t tree;
igraph_matrix_t sto;
igraph_matrix_t hess;
igraph_matrix_complex_t evec1, evec2;
igraph_vector_complex_t eval1, eval2;
igraph_eigen_which_t which;
int i;
igraph_tree(&tree, nodes, /* children= */ 3, IGRAPH_TREE_UNDIRECTED);
igraph_matrix_init(&sto, nodes, nodes);
igraph_get_stochastic(&tree, &sto, /*column_wise=*/ 0);
igraph_matrix_transpose(&sto);
igraph_matrix_init(&hess, nodes, nodes);
igraph_lapack_dgehrd(&sto, 1, nodes, &hess);
igraph_matrix_complex_init(&evec1, 0, 0);
igraph_vector_complex_init(&eval1, 0);
which.pos = IGRAPH_EIGEN_ALL;
igraph_eigen_matrix(&sto, 0, 0, nodes, 0, IGRAPH_EIGEN_LAPACK, &which, 0, 0,
&eval1, &evec1);
igraph_matrix_complex_init(&evec2, 0, 0);
igraph_vector_complex_init(&eval2, 0);
igraph_eigen_matrix(&hess, 0, 0, nodes, 0, IGRAPH_EIGEN_LAPACK, &which, 0,
0, &eval2, &evec2);
for (i=0; i<nodes; i++) {
igraph_real_t d=igraph_complex_abs(igraph_complex_sub(VECTOR(eval1)[i],
VECTOR(eval2)[i]));
if (d > 1e-14) { printf("Difference: %g\n", d); return 1; }
}
igraph_matrix_complex_destroy(&evec2);
igraph_vector_complex_destroy(&eval2);
igraph_matrix_complex_destroy(&evec1);
igraph_vector_complex_destroy(&eval1);
igraph_matrix_destroy(&hess);
igraph_matrix_destroy(&sto);
igraph_destroy(&tree);
return 0;
}
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