1 files changed, 13 insertions, 12 deletions
diff --git a/src/Persistence_representations/include/gudhi/Persistence_landscape_on_grid_exact.h b/src/Persistence_representations/include/gudhi/Persistence_landscape_on_grid_exact.h
index 25f71e27..52f24195 100644
--- a/src/Persistence_representations/include/gudhi/Persistence_landscape_on_grid_exact.h
+++ b/src/Persistence_representations/include/gudhi/Persistence_landscape_on_grid_exact.h
@@ -82,24 +82,25 @@ class Persistence_landscape_on_grid_exact {
     */
    std::vector<std::vector<double> > vectorize() const {
      std::vector<std::vector<double> >  ls; for(int i = 0; i < nb_ls; i++)  ls.emplace_back();
-     int num_pts = diagram.size(); double step = (max_x - min_x)/res_x;
+     int num_pts = diagram.size(); double step = (max_x - min_x)/(res_x - 1);
+
+     std::vector<std::vector<double> > ls_t; for(int i = 0; i < res_x; i++)  ls_t.emplace_back();
+     for(int j = 0; j < num_pts; j++){
+       double px = diagram[j].first; double py = diagram[j].second; double mid = (px+py)/2;
+       int first = std::ceil((px-min_x)/step); int middle = std::ceil((mid-min_x)/step); int last = std::ceil((py-min_x)/step); double x = min_x + first*step;
+       for(int i = first; i < middle; i++){  double value = std::sqrt(2)*(x-px); ls_t[i].push_back(value); x += step;  }
+       for(int i = middle; i < last; i++){   double value = std::sqrt(2)*(py-x); ls_t[i].push_back(value); x += step;  }
+     }
 
      for(int i = 0; i < res_x; i++){
-       double x = min_x + i*step; double t = x / std::sqrt(2); std::vector<double> events;
-       for(int j = 0; j < num_pts; j++){
-         double px = diagram[j].first; double py = diagram[j].second;
-         if(t >= px && t <= py){  if(t >= (px+py)/2)  events.push_back(std::sqrt(2)*(py-t)); else  events.push_back(std::sqrt(2)*(t-px));  }
-       }
-
-       std::sort(events.begin(), events.end(), [](const double & a, const double & b){return a > b;}); int nb_events = events.size();
-       for (int j = 0; j < nb_ls; j++){  if(j < nb_events)  ls[j].push_back(events[j]);  else  ls[j].push_back(0);  }
+       std::sort(ls_t[i].begin(), ls_t[i].end(), [](const double & a, const double & b){return a > b;});
+       int nb_events_i = ls_t[i].size();
+       for (int j = 0; j < nb_ls; j++){  if(j < nb_events_i)  ls[j].push_back(ls_t[i][j]);  else  ls[j].push_back(0);  }
      }
+
      return ls;
    }
 
-
-
-
 }; // class Persistence_landscape_on_grid_exact
 }  // namespace Persistence_representations
 }  // namespace Gudhi