[Merged by Bors] - feat: normalised Eisenstein series

[CBirkbeck]

define normalised Eisenstein series in preparation for giving their q-expansions.

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[github-actions]

PR summary 650e8b8fb3

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

+ E

You can run this locally as follows

## summary with just the declaration names:
./scripts/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/declarations_diff.sh long <optional_commit>

The doc-module for script/declarations_diff.sh contains some details about this script.

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No changes to technical debt.

You can run this locally as

./scripts/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[loefflerd]

I'd suggest the following:

• Don't use N : ℕ+, but instead N : ℕ with a [NeZero N] instance. This requires one tiny change elsewhere, in isBoundedAtImInfty_eisensteinSeries_SIF, and everything else just works. (You can get a proof of positivity of N with NeZero.pos N.) Then you can just write ZMod 1, not the ugly and tedious-to-type ZMod ((1 : ℕ+) : ℕ).
• Since standardCongruenceCondition is defined to be 0, why not just skip defining it and just write 0 directly (letting it be coerced implicitly to a vector)? Note that mathlib can synth a subsingleton instance for Fin 2 → ZMod 1, while it apparently can't for ZMod ((1 : ℕ+) : ℕ).
• mod_cast hk achieves the same as by omega but it's more obvious to the reader what it's doing.

BTW, I think the review process will go quicker if you make your PR's a little larger than this; I tend to aim for 200-500 lines at a time. If you slice things too finely it makes more work both for reviewers + for yourself (more tedious git merging).

[CBirkbeck]

Thanks! Yes this one was a bit too short I agree.

[loefflerd]

LGTM now

maintainer merge

[github-actions]

🚀 Pull request has been placed on the maintainer queue by loefflerd.

[riccardobrasca]

Thanks!

bors merge

[mathlib-bors]

Canceled.

[loefflerd]

Ouch, there's a weird build glitch in a file entirely unrelated to the PR; we should have a linter banning simp says.

@riccardobrasca can you do a bors delegate?

[riccardobrasca]

Thanks!

bors d+

[mathlib-bors]

✌️ CBirkbeck can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

[MichaelStollBayreuth]

Merging master should probably fix the problem.

[CBirkbeck]

bors r+

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

• CI Success