lilc_matrix_find_root.h

// -*- mode: c++ -*-
#ifndef _LILC_MATRIX_FIND_ROOT_H_
#define _LILC_MATRIX_FIND_ROOT_H_

template<class el_type> 
inline void lilc_matrix<el_type> :: find_root(int& s) {
    vector<bool> visited(m_n_cols, false);
    vector<int> lvl_set;
    int ls_max = 0, ls = 0;
    
    while (true) {
        lvl_set.clear();
        std::fill(visited.begin(), visited.end(), false);
        ls = 0;
        
        lvl_set.push_back(s);
        visited[s] = true;
        while (find_level_set(lvl_set, visited))
            ls++;

        if (ls > ls_max) {
            ls_max = ls;
            int deg, min_deg = m_n_cols;
            for (idx_it it = lvl_set.begin(); it != lvl_set.end(); it++) {
                deg = list[*it].size() + m_idx[*it].size();
                if (m_idx[*it].size() > 0 && m_idx[*it][0] == *it) deg--;
                if (deg < min_deg) { //should consider tie breaking by index later if needed.
                    min_deg = deg;
                    s = *it;
                }
            }
        } else {
            break;
        }
    }
}

#endif