# References
- <https://en.wikipedia.org/wiki/Test_functions_for_optimization>
- <https://www.sfu.ca/~ssurjano/index.html>
- <https://infinity77.net/global_optimization/test_functions.html#multidimensional-test-functions-index>
- <http://www-optima.amp.i.kyoto-u.ac.jp/member/student/hedar/Hedar_files/TestGO_files/Page364.htm>