/**
* 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 3 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, see
* .
*
* (c) Vincenzo Nicosia 2009-2017 --
*
* This file is part of NetBunch, a package for complex network
* analysis and modelling. For more information please visit:
*
* http://www.complex-networks.net/
*
* If you use this software, please add a reference to
*
* V. Latora, V. Nicosia, G. Russo
* "Complex Networks: Principles, Methods and Applications"
* Cambridge University Press (2017)
* ISBN: 9781107103184
*
***********************************************************************
*
* This program computes the leading eigenvector and the leading
* eigenvalue of a given graph, using the power method. The value of
* the leading eigenvalue is printed on the standard output, while
* the associated eigenvector is reported.
*
*
*/
#include
#include
#include
#include
#include "utils.h"
#define MAX(x,y) ((x)>(y)? (x) : (y))
void usage(char *argv[]){
printf("********************************************************************\n"
"** **\n"
"** -*- pm -*- **\n"
"** **\n"
"** Compute the leading eigenvalue and the leading eigenvector **\n"
"** of a graph, with a relative error smaller than 'eps' using **\n"
"** the power method (Rayleigh iteration). **\n"
"** **\n"
"** The input file 'graph_in' is an edge-list: **\n"
"** **\n"
"** I_1 J_1 **\n"
"** I_2 J_2 **\n"
"** I_3 J_3 **\n"
"** ... ... **\n"
"** I_K J_K **\n"
"** **\n"
"** If 'graph_in' is equal to '-' (dash), read the file from **\n"
"** the standard input (STDIN). **\n"
"** **\n"
"** 'is_dir' should be set either to 0 (zero) if the graph is **\n"
"** undirected, or to 1 (one) if the graph is directed. **\n"
"** **\n"
"** The value of the leading eigenvalue is printed on the **\n"
"** standard output (STDOUT) while the associated eigenvector **\n"
"** is printed on the standard error (STDERR). **\n"
"** **\n"
"** **\n"
"********************************************************************\n"
" This is Free Software - You can use and distribute it under \n"
" the terms of the GNU General Public License, version 3 or later\n\n"
" Please visit http://www.complex-networks.net for more information\n\n"
" (c) Vincenzo Nicosia 2010-2017 (v.nicosia@qmul.ac.uk)\n"
"********************************************************************\n\n"
);
printf("Usage: %s \n", argv[0]);
}
/* Product of a matrix by a vector */
void matrix_vector_product(unsigned int *I, unsigned int *J, unsigned int K,
double *src, double *dst, unsigned int N){
int i;
for(i=0; i eps) {
norm = vector_norm(x1, N);
for(i=0; i