I was surfing scipy's codebase on GitHub and I came across the following synthax for what seems to be a docstring:
class Salomon(Benchmark):
r"""
Salomon objective function.
This class defines the Salomon [1]_ global optimization problem. This is a
multimodal minimization problem defined as follows:
.. math::
f_{\text{Salomon}}(x) = 1 - \cos \left (2 \pi
\sqrt{\sum_{i=1}^{n} x_i^2} \right) + 0.1 \sqrt{\sum_{i=1}^n x_i^2}
Here, :math:`n` represents the number of dimensions and :math:`x_i \in
[-100, 100]` for :math:`i = 1, ..., n`.
*Global optimum*: :math:`f(x) = 0` for :math:`x_i = 0` for
:math:`i = 1, ..., n`
.. [1] Jamil, M. & Yang, X.-S. A Literature Survey of Benchmark Functions
For Global Optimization Problems Int. Journal of Mathematical Modelling
and Numerical Optimisation, 2013, 4, 150-194.
"""
For what is this r""" synthax used for? Why do not use normal """<docstring>""" or '''<docstring>'''?
