# Homework 4

Remember to include the folders `trajectories`, `pybind11` and `googletest`.
Also make a folder `build` which contains a folder named `dumps`.

### Exercise 1:
1.2: The role of function overloading `createSimulation` to associate one method or another one depending of the type or number of arguments that takes the method.

### Exercise 2:
2.2: To ensure that references are correctly managed to python bindings we used shared pointers: `std::shared_ptr<>`. Using this, the memory of these pointers will be DEALLOCATED when the python's reference goes to 0!

### Exercise 4:
Can run the example using the command    
`./particles 365 1 ../init.csv planet 1`   
or    
`python main.py 365 1 ../init.csv planet 1`   
from the `build` folder.
The gravitational constant G has been accordingly changed in the c++ code to give same results as python.

Note that we assume 5 integers in the filenames (e.g. `step-00000.csv`), i.e., not 4 as in the trajectory folder.
We can easily rename multiple files using the command `rename 's/step-0/step-00/g' *` in order to get same naming convention.

The trajectories can be viewed using Paraview, and we observe trajectories as expected. Except for Mercury.

### Exercise 5 through 7:
See the file `python_functions.py`.
Run the file from the `build` folder with `python ../python_functions.py`.    

We find that the scaling factor for Mercury's velocity is approximately 0.39.

NB: it is assumed that your python command is called `python` and not for example `python3`.