Xi function

[mayankray2020]

References to other Issues or PRs

Taking over #18483

• functions
  • riemaan xi function

[sympy-bot]

✅

Hi, I am the SymPy bot (v161). I'm here to help you write a release notes entry. Please read the guide on how to write release notes.

Your release notes are in good order.

Here is what the release notes will look like:

• functions
  • riemaan xi function (#20901 by @abh2k and @mayankray2020)

This will be added to https://github.com/sympy/sympy/wiki/Release-Notes-for-1.8.

Click here to see the pull request description that was parsed.

<!-- Your title above should be a short description of what
was changed. Do not include the issue number in the title. -->

#### References to other Issues or PRs
<!-- If this pull request fixes an issue, write "Fixes #NNNN" in that exact
format, e.g. "Fixes #1234" (see
https://tinyurl.com/auto-closing for more information). Also, please
write a comment on that issue linking back to this pull request once it is
open. -->
Taking over #18483 

<!-- BEGIN RELEASE NOTES -->
* functions
  * riemaan xi function
<!-- END RELEASE NOTES -->

Update

The release notes on the wiki have been updated.

[0sidharth]

You should add the function name to sympy/__init__.py also.

[0sidharth]

You also need to add to sympy/core/tests/test_args.py

[mayankray2020]

@0sidharth @czgdp1807 please review this.

[0sidharth]

LGTM.

[mayankray2020]

@0sidharth @czgdp1807 is it ready to merge??

[abhinav-anand-addepar]

LGTM.

[mayankray2020]

@czgdp1807 please review.

[oscarbenjamin]

Looks good