Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

[Merged by Bors] - feat(data/complex/exponential): bound on exp for arbitrary arguments #8667

Closed
wants to merge 34 commits into from

Conversation

BoltonBailey
Copy link
Collaborator

@BoltonBailey BoltonBailey commented Aug 14, 2021

This PR is for a new lemma (currently called exp_bound') which proves exp x is close to its nth degree taylor expansion for sufficiently large n. Unlike the previous bound, this lemma can be instantiated on any real x rather than just x with absolute value less than or equal to 1. I am separating this lemma out from #8002 because I think it stands on its own.

The last time I checked it was sorry free - but that was before I merged with master and moved it to a different branch. It may also benefit from a little golfing.

There are a few lemmas I proved as well to support this - one about the relative size of factorials and a few about sums of geometric sequences. The geometric series ones should probably be generalized and moved to another file this generalization sort of exists and is in the algebra.geom_sum file. I didn't find it initially since I was searching for "geometric" not "geom".


Open in Gitpod

@BoltonBailey BoltonBailey added the WIP Work in progress label Aug 14, 2021
@BoltonBailey BoltonBailey added awaiting-review The author would like community review of the PR and removed WIP Work in progress labels Aug 16, 2021
@semorrison semorrison changed the title Tight exp bound feat(src/data/complex/exponential): bound on exp for arbitrary arguments Aug 16, 2021
@semorrison
Copy link
Collaborator

Would it be possible to use a lemma characterising exp, rather than unfolding the definition using rw exp? My concern is that with things like #8576 (the exponential in any Banach algebra) in the works we may end up changing the definition underneath you.

@sgouezel sgouezel removed the awaiting-review The author would like community review of the PR label Aug 16, 2021
@BoltonBailey BoltonBailey added awaiting-review The author would like community review of the PR and removed awaiting-author A reviewer has asked the author a question or requested changes labels Aug 17, 2021
@BoltonBailey
Copy link
Collaborator Author

If #8576 is coming in the next few days, and you all think it's important to avoid changing this until it's done feel free to block this. Otherwise, I can also address any other comments about the code.

@bryangingechen bryangingechen changed the title feat(src/data/complex/exponential): bound on exp for arbitrary arguments feat(data/complex/exponential): bound on exp for arbitrary arguments Aug 17, 2021
src/algebra/big_operators/basic.lean Outdated Show resolved Hide resolved
src/algebra/group/basic.lean Outdated Show resolved Hide resolved
src/data/complex/exponential.lean Outdated Show resolved Hide resolved
@jcommelin jcommelin added awaiting-author A reviewer has asked the author a question or requested changes and removed awaiting-review The author would like community review of the PR labels Aug 18, 2021
BoltonBailey and others added 3 commits August 18, 2021 15:35
Co-authored-by: Johan Commelin <johan@commelin.net>
Co-authored-by: Johan Commelin <johan@commelin.net>
@BoltonBailey BoltonBailey added awaiting-review The author would like community review of the PR and removed awaiting-author A reviewer has asked the author a question or requested changes labels Aug 19, 2021
@jcommelin
Copy link
Member

I pushed a golf.

Copy link
Member

@jcommelin jcommelin left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Thanks 🎉

bors merge

@github-actions github-actions bot added ready-to-merge All that is left is for bors to build and merge this PR. (Remember you need to say `bors r+`.) and removed awaiting-review The author would like community review of the PR labels Aug 26, 2021
bors bot pushed a commit that referenced this pull request Aug 26, 2021
…8667)

This PR is for a new lemma (currently called `exp_bound'`) which proves `exp x` is close to its `n`th degree taylor expansion for sufficiently large `n`. Unlike the previous bound, this lemma can be instantiated on any real `x` rather than just `x` with absolute value less than or equal to 1. I am separating this lemma out from #8002 because I think it stands on its own.

The last time I checked it was sorry free - but that was before I merged with master and moved it to a different branch. It may also benefit from a little golfing.

There are a few lemmas I proved as well to support this - one about the relative size of factorials and a few about sums of geometric sequences. The ~~geometric series ones should probably be generalized and moved to another file~~ this generalization sort of exists and is in the algebra.geom_sum file. I didn't find it initially since I was searching for "geometric" not "geom".
@bors
Copy link

bors bot commented Aug 26, 2021

Pull request successfully merged into master.

Build succeeded:

@bors bors bot changed the title feat(data/complex/exponential): bound on exp for arbitrary arguments [Merged by Bors] - feat(data/complex/exponential): bound on exp for arbitrary arguments Aug 26, 2021
@bors bors bot closed this Aug 26, 2021
@bors bors bot deleted the tight-exp-bound branch August 26, 2021 08:57
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
ready-to-merge All that is left is for bors to build and merge this PR. (Remember you need to say `bors r+`.)
Projects
None yet
Development

Successfully merging this pull request may close these issues.

None yet

6 participants