diff options
Diffstat (limited to 'src/Bottleneck_distance/include/gudhi/Bottleneck.h')
-rw-r--r-- | src/Bottleneck_distance/include/gudhi/Bottleneck.h | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/src/Bottleneck_distance/include/gudhi/Bottleneck.h b/src/Bottleneck_distance/include/gudhi/Bottleneck.h index c34ea933..d7e11a05 100644 --- a/src/Bottleneck_distance/include/gudhi/Bottleneck.h +++ b/src/Bottleneck_distance/include/gudhi/Bottleneck.h @@ -34,6 +34,12 @@ double bottleneck_distance_approx(Persistence_graph& g, double e) { double b_lower_bound = 0.; double b_upper_bound = g.diameter_bound(); const double alpha = std::pow(g.size(), 1./5.); + if(e < std::numeric_limits<double>::epsilon() * alpha){ + e = std::numeric_limits<double>::epsilon() * alpha; +#ifdef DEBUG_TRACES + std::cout << "Epsilon user given value is less than eps_min. Forced to eps_min by the application" << std::endl; +#endif // DEBUG_TRACES + } Graph_matching m(g); Graph_matching biggest_unperfect(g); while (b_upper_bound - b_lower_bound > 2*e) { @@ -73,18 +79,18 @@ double bottleneck_distance_exact(Persistence_graph& g) { return sd.at(lower_bound_i); } -/** \brief Function to use in order to compute the Bottleneck distance between two persistence diagrams (see Concepts). - * If the last parameter e is not 0 (default value if not explicited), you get an additive e-approximation. +/** \brief Function to use in order to compute the Bottleneck distance between two persistence diagrams (see concepts). + * If the last parameter e is not 0, you get an additive e-approximation, which is a lot faster to compute whatever is e. + * Thus, by default, e is a very small positive double, actually the smallest double possible such that the floating-point inaccuracies don't lead to a failure of the algorithm. * * \ingroup bottleneck_distance */ template<typename Persistence_diagram1, typename Persistence_diagram2> -double bottleneck_distance(const Persistence_diagram1 &diag1, const Persistence_diagram2 &diag2, double e=0.) { +double bottleneck_distance(const Persistence_diagram1 &diag1, const Persistence_diagram2 &diag2, double e=std::numeric_limits<double>::epsilon()) { Persistence_graph g(diag1, diag2, e); if(g.bottleneck_alive() == std::numeric_limits<double>::infinity()) return std::numeric_limits<double>::infinity(); - double b = (e == 0. ? bottleneck_distance_exact(g) : bottleneck_distance_approx(g, e)); - return std::max(g.bottleneck_alive(),b); + return std::max(g.bottleneck_alive(), e == 0. ? bottleneck_distance_exact(g) : bottleneck_distance_approx(g, e)); } } // namespace persistence_diagram |