diff --git a/lemon/network_simplex.h b/lemon/network_simplex.h --- a/lemon/network_simplex.h +++ b/lemon/network_simplex.h @@ -636,11 +636,12 @@ /// The constructor of the class. /// /// \param graph The digraph the algorithm runs on. - /// \param arc_mixing Indicate if the arcs have to be stored in a + /// \param arc_mixing Indicate if the arcs will be stored in a /// mixed order in the internal data structure. - /// In special cases, it could lead to better overall performance, - /// but it is usually slower. Therefore it is disabled by default. - NetworkSimplex(const GR& graph, bool arc_mixing = false) : + /// In general, it leads to similar performance as using the original + /// arc order, but it makes the algorithm more robust and in special + /// cases, even significantly faster. Therefore, it is enabled by default. + NetworkSimplex(const GR& graph, bool arc_mixing = true) : _graph(graph), _node_id(graph), _arc_id(graph), _arc_mixing(arc_mixing), MAX(std::numeric_limits::max()), @@ -930,13 +931,13 @@ } if (_arc_mixing) { // Store the arcs in a mixed order - int k = std::max(int(std::sqrt(double(_arc_num))), 10); + const int skip = std::max(_arc_num / _node_num, 3); int i = 0, j = 0; for (ArcIt a(_graph); a != INVALID; ++a) { _arc_id[a] = i; _source[i] = _node_id[_graph.source(a)]; _target[i] = _node_id[_graph.target(a)]; - if ((i += k) >= _arc_num) i = ++j; + if ((i += skip) >= _arc_num) i = ++j; } } else { // Store the arcs in the original order