diff --git a/HW4/CMakeLists.txt b/HW4/CMakeLists.txt
index f589231..972f39b 100644
--- a/HW4/CMakeLists.txt
+++ b/HW4/CMakeLists.txt
@@ -1,101 +1,107 @@
 cmake_minimum_required (VERSION 3.1)
 project (Particles)
 cmake_policy(VERSION 3.3)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS 1)
 set(CMAKE_CXX_STANDARD 14)
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${PROJECT_SOURCE_DIR}/cmake")
 
 ################################################################
 # FFTW
 ################################################################
 
 #find_package(FFTW)
 # FFTW3 Check on/off - on by default
 option (FFTW_ENABLE "Use FFTW Library" ON) 
 if (FFTW_ENABLE)
     # Find the library
     find_library(FFT_LIBRARY fftw3)
 endif (FFTW_ENABLE)
 
 ################################################################
 # Pybind11
 ################################################################
 
 # (attached file "pybind11")
 
 option (PYBIND_ENABLE "Use FFTW Library" ON) 
 if (PYBIND_ENABLE)
-    # Add the library
+    # Add the library by subdirectory -> For Ubuntu
     add_subdirectory(pybind11)
+
+    # Link the wrapper library
+    add_library(pypart MODULE py_wrap.cc)
+    target_link_libraries(pypart PRIVATE pybind11::module)
+    set_target_properties(pypart PROPERTIES PREFIX "${PYTHON_MODULE_PREFIX}"
+                                           SUFFIX "${PYTHON_MODULE_EXTENSION}")
     # Copy main.py file to the binaries directory
     file(
         COPY ${CMAKE_CURRENT_SOURCE_DIR}/main.py
         DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/
     )
 endif (PYBIND_ENABLE)
 ################################################################
 # libpart
 ################################################################
 
 add_library(part SHARED
   compute_boundary.cc
   compute_verlet_integration.cc 
   particle.cc 
   planet.cc
   compute_gravity.cc 
   csv_reader.cc 
   particles_factory_interface.cc 
   planets_factory.cc 
   compute_contact.cc 
   compute_kinetic_energy.cc 
   csv_writer.cc 
   system.cc 
   compute_energy.cc 
   compute_potential_energy.cc 
   ping_pong_ball.cc
   material_point.cc 
   system_evolution.cc 
   ping_pong_balls_factory.cc 
   compute_interaction.cc
   compute_temperature.cc
   material_points_factory.cc 
   )
 
 target_link_libraries(part ${FFTW_LIBRARIES})
 add_executable(particles main.cc)
 target_link_libraries(particles part)
 
 ################################################################
 # Google test
 ################################################################
 
 
 include(GoogleTest)
 enable_testing()
 find_package(GTest)
 if (GTEST_FOUND)
 include_directories(${GTEST_INCLUDE_DIRS})
 add_executable(test_kepler test_kepler.cc)
 add_executable(test_fft test_fft.cc)
 target_link_libraries(test_kepler part ${GTEST_BOTH_LIBRARIES} pthread)
 target_link_libraries(test_fft part ${GTEST_BOTH_LIBRARIES} ${FFTW_LIBRARIES} pthread)
 gtest_discover_tests(test_kepler)
 gtest_discover_tests(test_fft)
 endif()
 
 ################################################################
 # Doxygen
 ################################################################
 
 find_package(Doxygen)
 if (DOXYGEN_FOUND)
 
 # to set other options, read: https://cmake.org/cmake/help/v3.9/module/FindDoxygen.html
 doxygen_add_docs(
     doxygen
     ${PROJECT_SOURCE_DIR}
     COMMENT "Generate html pages"
 )
 add_custom_target(doc DEPENDS doxygen)
 endif(DOXYGEN_FOUND)
diff --git a/HW4/py_wrap.cc b/HW4/py_wrap.cc
index 00f5b3e..68902af 100644
--- a/HW4/py_wrap.cc
+++ b/HW4/py_wrap.cc
@@ -1,72 +1,71 @@
 #include <iostream>
 #include <pybind11/pybind11.h>
 #include "material_points_factory.hh"
 #include "ping_pong_balls_factory.hh"
-#include "particle_factory.hh"
-#include "planet_factory.hh"
+#include "particles_factory_interface.hh"
+#include "planets_factory.hh"
 #include "compute_temperature.hh"
 #include "csv_writer.hh"
 
 // All the classes which are to be used in python are included here, together with the needed external library.
 
 namespace py = pybind11;
 
 //Start of the pybind module:
 
 PYBIND11_MODULE(pypart,m) {
-	m.doc="Using the pybind plugin";
-
+	m.doc()="This file is to wrap the C++ library over a Python API for the particles project.";
 
     py::class_<MaterialPointsFactory, ParticlesFactoryInterface>(m, "MaterialPointsFactory")
             .def("getInstance", &MaterialPointsFactory::getInstance,
                     py::return_value_policy::reference)
             .def("createSimulation",
                     (SystemEvolution & (MaterialPointsFactory::*)(const std::string &, Real))
                     &MaterialPointsFactory::createSimulation, py::return_value_policy::reference)
-            
+
             .def("createSimulation", py::overload_cast<const std::string&, Real, py::function>
                     (&MaterialPointsFactory::createSimulation<py::function>),
-                    py::return_value_policy::reference); 
+                    py::return_value_policy::reference);
 
-// In this case py::overload_cast operator has been used. The reason is that otherwise compiler can not know which method to use and thus produces the error. 
+// In this case py::overload_cast operator has been used. The reason is that otherwise compiler can not know which method to use and thus produces the error.
 // In Python method overloading does not exist in the same way like in c++ (there is no overloading resolution by the compiler obviously), thus we use py::overload_cast.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 }