diff --git a/README.md b/README.md
index afdd7cb5..3a26112c 100644
--- a/README.md
+++ b/README.md
@@ -1,47 +1,50 @@
 # SP4E Homeworks
 Students:  
 * Lars B.
 * Bertil T.
 
 In this repository, we will keep all homeworks for SP4E
 
 ## Homework 1
 See folder named *hw1-conjugate-gradient*.   
 
 #### Requirements
 * Numpy
 * Scipy
 * Matplotlib
 * Argparse
 
 The code as been tested with Python 3.
 
 #### Usage
 Run the *main_minimize.py* with the following arguments:
 * -A < matrix elements in row major order >
 * -b < vector elements >
 * -x0 < initial guess elements >
 * -method < CG-scipy or CG-ours >
 * -plot < True or False >
 
 #### Example
 
 The following command will run the program with the coefficients given in Exercise 1:  
 
 python3 main_minimize.py -A 8 0 2 6 -b 0 1 -x0 4 4 -method CG-scipy -plot True   
 
 NB: Note that the quadratic function in Exercise 1 is implemented with a multiplicative factor 1/2 in order to be consistent with Exercise 2.
 
 The following command will run the program with a 2x2 s.p.d. matrix A and 2-dim vector b using our self-implemented conjugate gradient method for solving the LSE Ax=b:
 
 python3 main_minimize.py -A  3 0 0 4 -b 4 5 -x0 12 12 -plot True -method CG-ours
 
 NB: Note that A must be s.p.d. in order for the conjugate gradient method to correctly solve Ax=b. Thus, the matrix A in Exercise 1 should not be used to compare the Scipy version (CG-scipy) againts our version (CG-ours). In the output of Exercise 1, you will see that it does not solve the LSE Ax=b (i.e., the residual outputted is high).
 
 NB: Plotting can only be accomplished in 1D (A and b are both scalars) or 2D (A is a 2x2 matrix and b is a 2-dim vector) as it is not possible to plot higher dimensional problems in a way that makes sense.
 
 ## Homework 2
 See the **homework2/**  folder and the instructions within its own README file.
 
 ## Homework 3
 See the **hw3-heat-fft/**  folder and the instructions within its own README file.
+
+## Homework 4
+See the **hw4-pybind/**  folder and the instructions within its own README file.
diff --git a/hw4-pybind/README.md b/hw4-pybind/README.md
new file mode 100644
index 00000000..9f509922
--- /dev/null
+++ b/hw4-pybind/README.md
@@ -0,0 +1,10 @@
+
+# Homework 4
+
+### Exercise 4:
+Can run the example using the command `./particles 365 1 ../init.csv planet 1` from the `build` folder. From C++ the gravitational constant G must be changed accordingly.
+
+The trajectories can be viewed using Paraview, and we observe trajectories as expected. Except for Mercury.
+
+### Exercise 5:
+See the file `python_functions.py`.