We have a loss of precision with the low-rank approximation in uniform and...

We have a loss of precision with the low-rank approximation in uniform and Chebyshev compared to dense and fft

checks/check_smooth_kernel.cpp

@@ -104,6 +104,7 @@ auto run(ParserType const& parser) -> void
     using near_field_type = scalfmm::operators::near_field_operator<matrix_kernel_type>;
     using interpolator_type = scalfmm::interpolation::interpolator<value_type, dimension, matrix_kernel_type,
                                                                    scalfmm::options::uniform_<scalfmm::options::fft_>>;
+    //    scalfmm::options::chebyshev_<scalfmm::options::low_rank_>>;
     using far_field_type = scalfmm::operators::far_field_operator<interpolator_type>;
     using fmm_operator_type = scalfmm::operators::fmm_operators<near_field_type, far_field_type>;
 
@@ -157,8 +158,8 @@ auto run(ParserType const& parser) -> void
     near_field_type near_field{};
 
     // a reference on the matrix_kernel of the near_field
-    auto near_mk = near_field.matrix_kernel();
-    // near_mk.set_coeff(2.0);
+    auto& near_mk = near_field.matrix_kernel();
+    near_mk.set_coeff(2.0);
 
     // build the approximation used in the near field
     interpolator_type interpolator(near_mk, order, tree_height, box.width(0));
@@ -166,6 +167,11 @@ auto run(ParserType const& parser) -> void
     //  construct the fmm operator
     fmm_operator_type fmm_operator(near_field, far_field);
 
+    std::cout << cpp_tools::colors::blue << "Fmm with kernels: " << std::endl
+              << "       near " << near_mk.name() << " mutual " << std::boolalpha << near_field.mutual() << std::endl
+              << "       far  " << far_field.approximation().matrix_kernel().name() << std::endl
+              << cpp_tools::colors::reset;
+
     const std::size_t group_size{10};   // the number of cells and leaf grouped in the tree
     group_tree_type tree(tree_height, order, box, group_size, group_size, container);
 
@@ -178,7 +184,7 @@ auto run(ParserType const& parser) -> void
 #ifdef PART_VAR
 
     scalfmm::component::for_each_leaf(std::cbegin(tree), std::cend(tree),
-                                      [&container, &container_debug, &error](auto const& leaf)
+                                      [&container, &error](auto const& leaf)
                                       {
                                           // loop on the particles of the leaf
                                           for(auto const p_ref: leaf)