Numerical methods have been first grouped into files having common numerical operation.
Each file has classes which defines a class of numerical operation which in turn supports several methods.
Any method can be used by importing the enclosing class (and it's dependencies if any) and running an instance of the same.
main part of the code was meant to solve the given assignment. Not necessary for running the methods.
Feel free to create an issue describing standard questions like "What's the problem?", "Expected answer", etc
Solve issues, or suggest new additions (and send PR :D ).