From b829a198e16fbef4c0cb2698b2c723fa353aac55 Mon Sep 17 00:00:00 2001
From: Hind-M <hind.montassif@gmail.com>
Date: Fri, 24 Jun 2022 11:03:22 +0200
Subject: Use CGAL::NT_converter instead of CGAL::to_double in
 Sphere_circumradius

---
 src/Cech_complex/include/gudhi/Cech_complex.h         |  2 +-
 src/Cech_complex/include/gudhi/Cech_complex_blocker.h |  1 +
 src/Cech_complex/include/gudhi/Sphere_circumradius.h  | 15 +++++++++------
 src/Cech_complex/test/test_cech_complex.cpp           |  4 ++--
 4 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/Cech_complex/include/gudhi/Cech_complex.h b/src/Cech_complex/include/gudhi/Cech_complex.h
index bae21d28..08b7a72f 100644
--- a/src/Cech_complex/include/gudhi/Cech_complex.h
+++ b/src/Cech_complex/include/gudhi/Cech_complex.h
@@ -70,7 +70,7 @@ class Cech_complex {
     point_cloud_.assign(std::begin(points), std::end(points));
 
     cech_skeleton_graph_ = Gudhi::compute_proximity_graph<SimplicialComplexForCechComplex>(
-        point_cloud_, max_radius_, Sphere_circumradius<Kernel>());
+        point_cloud_, max_radius_, Sphere_circumradius<Kernel, Filtration_value>());
   }
 
   /** \brief Initializes the simplicial complex from the proximity graph and expands it until a given maximal
diff --git a/src/Cech_complex/include/gudhi/Cech_complex_blocker.h b/src/Cech_complex/include/gudhi/Cech_complex_blocker.h
index 9cd49a52..25d9a71f 100644
--- a/src/Cech_complex/include/gudhi/Cech_complex_blocker.h
+++ b/src/Cech_complex/include/gudhi/Cech_complex_blocker.h
@@ -12,6 +12,7 @@
 #define CECH_COMPLEX_BLOCKER_H_
 
 #include <CGAL/NT_converter.h> // for casting from FT to Filtration_value
+#include <CGAL/Lazy_exact_nt.h> // for CGAL::exact
 
 #include <iostream>
 #include <vector>
diff --git a/src/Cech_complex/include/gudhi/Sphere_circumradius.h b/src/Cech_complex/include/gudhi/Sphere_circumradius.h
index b0d9f7cc..790f6950 100644
--- a/src/Cech_complex/include/gudhi/Sphere_circumradius.h
+++ b/src/Cech_complex/include/gudhi/Sphere_circumradius.h
@@ -11,7 +11,7 @@
 #ifndef SPHERE_CIRCUMRADIUS_H_
 #define SPHERE_CIRCUMRADIUS_H_
 
-#include <CGAL/Epeck_d.h> // for #include <CGAL/NewKernel_d/KernelD_converter.h>
+#include <CGAL/Epick_d.h> // for #include <CGAL/NT_converter.h> which is not working/compiling alone
 
 #include <cmath>  // for std::sqrt
 #include <vector>
@@ -22,14 +22,17 @@ namespace cech_complex {
 
 /** \private @brief Compute the circumradius of the sphere passing through points given by a range of coordinates.
  * The points are assumed to have the same dimension. */
-template<typename Kernel>
+template<typename Kernel, typename Filtration_value>
 class Sphere_circumradius {
  private:
     Kernel kernel_;
  public:
+    using FT = typename Kernel::FT;
     using Point = typename Kernel::Point_d;
     using Point_cloud = typename std::vector<Point>;
 
+    CGAL::NT_converter<FT, Filtration_value> cast_to_fv;
+
    /** \brief Circumradius of sphere passing through two points using CGAL.
    *
    * @param[in] point_1
@@ -38,8 +41,8 @@ class Sphere_circumradius {
    * \tparam Point must be a Kernel::Point_d from CGAL.
    *
    */
-  double operator()(const Point& point_1, const Point& point_2) const {
-    return std::sqrt(CGAL::to_double(kernel_.squared_distance_d_object()(point_1, point_2))) / 2.;
+  Filtration_value operator()(const Point& point_1, const Point& point_2) const {
+    return std::sqrt(cast_to_fv(kernel_.squared_distance_d_object()(point_1, point_2))) / 2.;
   }
 
   /** \brief Circumradius of sphere passing through point cloud using CGAL.
@@ -49,8 +52,8 @@ class Sphere_circumradius {
    * \tparam Point_cloud must be a range of Kernel::Point_d points from CGAL.
    *
    */
-  double operator()(const Point_cloud& point_cloud) const {
-    return std::sqrt(CGAL::to_double(kernel_.compute_squared_radius_d_object()(point_cloud.begin(), point_cloud.end())));
+  Filtration_value operator()(const Point_cloud& point_cloud) const {
+    return std::sqrt(cast_to_fv(kernel_.compute_squared_radius_d_object()(point_cloud.begin(), point_cloud.end())));
   }
 
 };
diff --git a/src/Cech_complex/test/test_cech_complex.cpp b/src/Cech_complex/test/test_cech_complex.cpp
index ea32f596..f5980e6d 100644
--- a/src/Cech_complex/test/test_cech_complex.cpp
+++ b/src/Cech_complex/test/test_cech_complex.cpp
@@ -107,11 +107,11 @@ BOOST_AUTO_TEST_CASE(Cech_complex_for_documentation) {
         std::clog << vertex << ",";
         vp.push_back(points.at(vertex));
       }
-      std::clog << ") - distance =" << Gudhi::cech_complex::Sphere_circumradius<Kernel>()(vp.at(0), vp.at(1))
+      std::clog << ") - distance =" << Gudhi::cech_complex::Sphere_circumradius<Kernel, Filtration_value>()(vp.at(0), vp.at(1))
                 << " - filtration =" << st.filtration(f_simplex) << std::endl;
       BOOST_CHECK(vp.size() == 2);
       GUDHI_TEST_FLOAT_EQUALITY_CHECK(st.filtration(f_simplex),
-                                      Gudhi::cech_complex::Sphere_circumradius<Kernel>()(vp.at(0), vp.at(1)));
+                                      Gudhi::cech_complex::Sphere_circumradius<Kernel, Filtration_value>()(vp.at(0), vp.at(1)));
     }
   }
 
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