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diff --git a/src/Persistence_representations/example/persistence_heat_maps.cpp b/src/Persistence_representations/example/persistence_heat_maps.cpp
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+/*    This file is part of the Gudhi Library - https://gudhi.inria.fr/ - which is released under MIT.
+ *    See file LICENSE or go to https://gudhi.inria.fr/licensing/ for full license details.
+ *    Author(s):       Pawel Dlotko and Mathieu Carriere
+ *
+ *    Copyright (C) 2019 Inria
+ *
+ *    Modifications:
+ *      - 2018/04 MC: Add persistence heat maps computation
+ *
+ *    Modification(s):
+ *      - YYYY/MM Author: Description of the modification
+ */
+
+#include <gudhi/Persistence_heat_maps.h>
+#include <gudhi/common_persistence_representations.h>
+
+#include <iostream>
+#include <vector>
+#include <utility>
+#include <functional>
+#include <cmath>
+
+std::function<double(std::pair<double, double>, std::pair<double, double>)> Gaussian_function(double sigma) {
+  return [=](std::pair<double, double> p, std::pair<double, double> q) {
+    return std::exp(-((p.first - q.first) * (p.first - q.first) + (p.second - q.second) * (p.second - q.second)) /
+                    (sigma));
+  };
+}
+
+using constant_scaling_function = Gudhi::Persistence_representations::constant_scaling_function;
+using Persistence_heat_maps = Gudhi::Persistence_representations::Persistence_heat_maps<constant_scaling_function>;
+
+int main(int argc, char** argv) {
+  // create two simple vectors with birth--death pairs:
+
+  std::vector<std::pair<double, double> > persistence1;
+  std::vector<std::pair<double, double> > persistence2;
+
+  persistence1.push_back(std::make_pair(1, 2));
+  persistence1.push_back(std::make_pair(6, 8));
+  persistence1.push_back(std::make_pair(0, 4));
+  persistence1.push_back(std::make_pair(3, 8));
+
+  persistence2.push_back(std::make_pair(2, 9));
+  persistence2.push_back(std::make_pair(1, 6));
+  persistence2.push_back(std::make_pair(3, 5));
+  persistence2.push_back(std::make_pair(6, 10));
+
+  // over here we define a function we sill put on a top on every birth--death pair in the persistence interval. It can
+  // be anything. Over here we will use standard Gaussian
+  std::vector<std::vector<double> > filter = Gudhi::Persistence_representations::create_Gaussian_filter(5, 1);
+
+  // creating two heat maps.
+  Persistence_heat_maps hm1(persistence1, filter, false, 20, 0, 11);
+  Persistence_heat_maps hm2(persistence2, filter, false, 20, 0, 11);
+
+  std::vector<Persistence_heat_maps*> vector_of_maps;
+  vector_of_maps.push_back(&hm1);
+  vector_of_maps.push_back(&hm2);
+
+  // compute median/mean of a vector of heat maps:
+  Persistence_heat_maps mean;
+  mean.compute_mean(vector_of_maps);
+  Persistence_heat_maps median;
+  median.compute_median(vector_of_maps);
+
+  // to compute L^1 distance between hm1 and hm2:
+  std::cout << "The L^1 distance is : " << hm1.distance(hm2, 1) << std::endl;
+
+  // to average of hm1 and hm2:
+  std::vector<Persistence_heat_maps*> to_average;
+  to_average.push_back(&hm1);
+  to_average.push_back(&hm2);
+  Persistence_heat_maps av;
+  av.compute_average(to_average);
+
+  // to compute scalar product of hm1 and hm2:
+  std::cout << "Scalar product is : " << hm1.compute_scalar_product(hm2) << std::endl;
+
+  Persistence_heat_maps hm1k(persistence1, Gaussian_function(1.0));
+  Persistence_heat_maps hm2k(persistence2, Gaussian_function(1.0));
+  Persistence_heat_maps hm1i(persistence1, Gaussian_function(1.0), 20, 20, 0, 11, 0, 11);
+  Persistence_heat_maps hm2i(persistence2, Gaussian_function(1.0), 20, 20, 0, 11, 0, 11);
+  std::cout << "Scalar product computed with exact 2D kernel on grid is : " << hm1i.compute_scalar_product(hm2i)
+            << std::endl;
+  std::cout << "Scalar product computed with exact 2D kernel is : " << hm1k.compute_scalar_product(hm2k) << std::endl;
+
+  return 0;
+}