Re-organize math/series

[atharva01903]

Describe your change:

Added the implementation of harmonic mean.

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[atharva01903]

@poyea @dhruvmanila Hello, can anyone of you please review my contribution to this repository? I'll be glad to get some suggestions and learn from them,

Thanks.

[atharva01903]

Thanks @poyea for the suggestion and reviewing my code :) I've made the change. Also, I checked other implementations in the the /maths/series folder. In the implementation of arithmetic mean and geometric mean, the code first checks if a series is an arithmetic or a geometric series respectively. But arithmetic and geometric mean can be computed without the series actually being an arithmetic and a geometric series respectively. So the condition that requires a series to follow arithmetic or geometric progression should be removed. Should I proceed to make that change?

[poyea]

Yes, you may make those changes on this branch.

[atharva01903]

Thank you so much @poyea for the approval. I have incorporated the changes to the branch. 😊👍🏼

[atharva01903]

@poyea Ah yes, we can do that as well! I think it is better to add the methods is_arithmetic_series and is_geometric_series to a new file arithmetic_series.py (as it isn't available in the repository) and geometric_series.py respectively. So along with the implementation we can also check if the series is arithmetic/geometric. With that we can add one more method is_harmonic_series to the file harmonic_series.py. Do tell me if you need those changes.

[poyea]

@poyea Ah yes, we can do that as well! I think it is better to add the methods is_arithmetic_series and is_geometric_series to a new file arithmetic_series.py (as it isn't available in the repository) and geometric_series.py respectively. So along with the implementation we can also check if the series is arithmetic/geometric. With that we can add one more method is_harmonic_series to the file harmonic_series.py. Do tell me if you need those changes.

@atharva01903 Let's do it this way:
In maths/series/, we make 3 files: arithmetic.py, geometric.py and harmonic.py. Then add the mean and is_series functions is each of the files.

[atharva01903]

Alright @poyea, I did that. Now the mean and is_series functions lie in a single file. 👍🏼

[poyea]

Thank you for your pull request!🤩