[REVIEW]: Krang: Kerr Raytracer for Analytic Null Geodesics

[editorialbot]

Submitting author: @dominic-chang (Dominic Chang)
Repository: https://github.com/dominic-chang/Krang.jl
Branch with paper.md (empty if default branch): joss-paper
Version: v0.3.1
Editor: @lrnv
Reviewers: @aplavin, @alejandroc137, @ExpandingMan
Archive: 10.5281/zenodo.13936258

Status

Status badge code:

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Markdown: [![status](https://joss.theoj.org/papers/378df5c54cd21e293b92ac692c21c0ed/status.svg)](https://joss.theoj.org/papers/378df5c54cd21e293b92ac692c21c0ed)

Reviewers and authors:

Please avoid lengthy details of difficulties in the review thread. Instead, please create a new issue in the target repository and link to those issues (especially acceptance-blockers) by leaving comments in the review thread below. (For completists: if the target issue tracker is also on GitHub, linking the review thread in the issue or vice versa will create corresponding breadcrumb trails in the link target.)

Reviewer instructions & questions

@aplavin & @alejandroc137 & @ExpandingMan, your review will be checklist based. Each of you will have a separate checklist that you should update when carrying out your review.
First of all you need to run this command in a separate comment to create the checklist:

@editorialbot generate my checklist

The reviewer guidelines are available here: https://joss.readthedocs.io/en/latest/reviewer_guidelines.html. Any questions/concerns please let @lrnv know.

✨ Please start on your review when you are able, and be sure to complete your review in the next six weeks, at the very latest ✨

Checklists

📝 Checklist for @aplavin

📝 Checklist for @alejandroc137

📝 Checklist for @ExpandingMan

[editorialbot]

Hello humans, I'm @editorialbot, a robot that can help you with some common editorial tasks.

For a list of things I can do to help you, just type:

@editorialbot commands

For example, to regenerate the paper pdf after making changes in the paper's md or bib files, type:

@editorialbot generate pdf

[editorialbot]

Reference check summary (note 'MISSING' DOIs are suggestions that need verification):

✅ OK DOIs

- 10.1137/141000671 is OK
- 10.1126/sciadv.aaz1310 is OK
- 10.3847/2041-8213/ab0ec7 is OK
- 10.3847/2041-8213/ab0c96 is OK
- 10.3847/2041-8213/ac6674 is OK
- 10.1103/PhysRevD.107.043030 is OK
- 10.3847/1538-4357/ac9ab7 is OK
- 10.5281/ZENODO.6471796 is OK

🟡 SKIP DOIs

- None

❌ MISSING DOIs

- 10.1117/12.3019437 may be a valid DOI for title: The Black Hole Explorer: Photon Ring Science, Dete...

❌ INVALID DOIs

- None

[editorialbot]

Software report:

github.com/AlDanial/cloc v 1.90  T=0.05 s (1172.8 files/s, 168527.8 lines/s)
-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
Julia                           31            711            547           3042
JSON                             2              0              0           2340
Markdown                         9             97              0            629
YAML                             6              5              9            201
CSS                              1             38             28            115
TeX                              1              0              0            109
Vuejs Component                  1              2              3             83
TOML                             4              5              0             62
TypeScript                       1              2              2             17
-------------------------------------------------------------------------------
SUM:                            56            860            589           6598
-------------------------------------------------------------------------------

Commit count by author:

    54	Dominic
    37	dominic-chang
    34	Dominic Chang
     5	CompatHelper Julia
     1	Anshul Singhvi
     1	Paul Tiede

[editorialbot]

Paper file info:

📄 Wordcount for paper.md is 691

✅ The paper includes a Statement of need section

[editorialbot]

License info:

✅ License found: MIT License (Valid open source OSI approved license)

[editorialbot]

👉📄 Download article proof 📄 View article proof on GitHub 📄 👈

[lrnv]

👋🏼 @dominic-chang, @aplavin, @ExpandingMan, @alejandroc137: this is the review thread for the paper. All of our communications will happen here from now on, so that each of us can read what each other writes.

@aplavin, @ExpandingMan, @alejandroc137, as reviewers, your first step is to create a checklist for yourself, to guide you through the review, by commenting

@editorialbot generate my checklist

on this thread.

These checklists contain the JOSS requirements. As you go over the submission, please check any items that you feel have been satisfied. The first comment in this thread also contains links to the JOSS reviewer guidelines.

The JOSS review is different from most other journals. Our goal is to work with the authors to help them meet our criteria instead of merely passing judgment on the submission. As such, the reviewers are encouraged to submit issues and pull requests on the software repository. When doing so, please mention #7273 so that a link is created to this thread (and I can keep an eye on what is happening). Please also feel free to comment and ask questions on this thread. In my experience, it is better to post comments/questions/suggestions as you come across them instead of waiting until you've reviewed the entire package.

We aim for reviews to be completed within about 2-4 weeks. Please let me know if any of you require some more time. We can also use @editorialbot (our bot) to set automatic reminders if you know you'll be away for a known period of time.

Please feel free to ping me (@lrnv) if you have any questions/concerns, if something is unclear, or if you need more info about the process :)

[alejandroc137]

Review checklist for @alejandroc137

Conflict of interest

• I confirm that I have read the JOSS conflict of interest (COI) policy and that: I have no COIs with reviewing this work or that any perceived COIs have been waived by JOSS for the purpose of this review.

Code of Conduct

• I confirm that I read and will adhere to the JOSS code of conduct.

General checks

• Repository: Is the source code for this software available at the https://github.com/dominic-chang/Krang.jl?
• License: Does the repository contain a plain-text LICENSE or COPYING file with the contents of an OSI approved software license?
• Contribution and authorship: Has the submitting author (@dominic-chang) made major contributions to the software? Does the full list of paper authors seem appropriate and complete?
• Substantial scholarly effort: Does this submission meet the scope eligibility described in the JOSS guidelines
• Data sharing: If the paper contains original data, data are accessible to the reviewers. If the paper contains no original data, please check this item.
• Reproducibility: If the paper contains original results, results are entirely reproducible by reviewers. If the paper contains no original results, please check this item.
• Human and animal research: If the paper contains original data research on humans subjects or animals, does it comply with JOSS's human participants research policy and/or animal research policy? If the paper contains no such data, please check this item.

Functionality

• Installation: Does installation proceed as outlined in the documentation?
• Functionality: Have the functional claims of the software been confirmed?
• Performance: If there are any performance claims of the software, have they been confirmed? (If there are no claims, please check off this item.)

Documentation

• A statement of need: Do the authors clearly state what problems the software is designed to solve and who the target audience is?
• Installation instructions: Is there a clearly-stated list of dependencies? Ideally these should be handled with an automated package management solution.
• Example usage: Do the authors include examples of how to use the software (ideally to solve real-world analysis problems).
• Functionality documentation: Is the core functionality of the software documented to a satisfactory level (e.g., API method documentation)?
• Automated tests: Are there automated tests or manual steps described so that the functionality of the software can be verified?
• Community guidelines: Are there clear guidelines for third parties wishing to 1) Contribute to the software 2) Report issues or problems with the software 3) Seek support

Software paper

• Summary: Has a clear description of the high-level functionality and purpose of the software for a diverse, non-specialist audience been provided?
• A statement of need: Does the paper have a section titled 'Statement of need' that clearly states what problems the software is designed to solve, who the target audience is, and its relation to other work?
• State of the field: Do the authors describe how this software compares to other commonly-used packages?
• Quality of writing: Is the paper well written (i.e., it does not require editing for structure, language, or writing quality)?
• References: Is the list of references complete, and is everything cited appropriately that should be cited (e.g., papers, datasets, software)? Do references in the text use the proper citation syntax?

[aplavin]

Review checklist for @aplavin

Conflict of interest

• I confirm that I have read the JOSS conflict of interest (COI) policy and that: I have no COIs with reviewing this work or that any perceived COIs have been waived by JOSS for the purpose of this review.

Code of Conduct

• I confirm that I read and will adhere to the JOSS code of conduct.

General checks

• Repository: Is the source code for this software available at the https://github.com/dominic-chang/Krang.jl?
• License: Does the repository contain a plain-text LICENSE or COPYING file with the contents of an OSI approved software license?
• Contribution and authorship: Has the submitting author (@dominic-chang) made major contributions to the software? Does the full list of paper authors seem appropriate and complete?
• Substantial scholarly effort: Does this submission meet the scope eligibility described in the JOSS guidelines
• Data sharing: If the paper contains original data, data are accessible to the reviewers. If the paper contains no original data, please check this item.
• Reproducibility: If the paper contains original results, results are entirely reproducible by reviewers. If the paper contains no original results, please check this item.
• Human and animal research: If the paper contains original data research on humans subjects or animals, does it comply with JOSS's human participants research policy and/or animal research policy? If the paper contains no such data, please check this item.

Functionality

• Installation: Does installation proceed as outlined in the documentation?
• Functionality: Have the functional claims of the software been confirmed?
• Performance: If there are any performance claims of the software, have they been confirmed? (If there are no claims, please check off this item.)

Documentation

• A statement of need: Do the authors clearly state what problems the software is designed to solve and who the target audience is?
• Installation instructions: Is there a clearly-stated list of dependencies? Ideally these should be handled with an automated package management solution.
• Example usage: Do the authors include examples of how to use the software (ideally to solve real-world analysis problems).
• Functionality documentation: Is the core functionality of the software documented to a satisfactory level (e.g., API method documentation)?
• Automated tests: Are there automated tests or manual steps described so that the functionality of the software can be verified?
• Community guidelines: Are there clear guidelines for third parties wishing to 1) Contribute to the software 2) Report issues or problems with the software 3) Seek support

Software paper

• Summary: Has a clear description of the high-level functionality and purpose of the software for a diverse, non-specialist audience been provided?
• A statement of need: Does the paper have a section titled 'Statement of need' that clearly states what problems the software is designed to solve, who the target audience is, and its relation to other work?
• State of the field: Do the authors describe how this software compares to other commonly-used packages?
• Quality of writing: Is the paper well written (i.e., it does not require editing for structure, language, or writing quality)?
• References: Is the list of references complete, and is everything cited appropriately that should be cited (e.g., papers, datasets, software)? Do references in the text use the proper citation syntax?

[ExpandingMan]

Review checklist for @ExpandingMan

Conflict of interest

• I confirm that I have read the JOSS conflict of interest (COI) policy and that: I have no COIs with reviewing this work or that any perceived COIs have been waived by JOSS for the purpose of this review.

Code of Conduct

• I confirm that I read and will adhere to the JOSS code of conduct.

General checks

• Repository: Is the source code for this software available at the https://github.com/dominic-chang/Krang.jl?
• License: Does the repository contain a plain-text LICENSE or COPYING file with the contents of an OSI approved software license?
• Contribution and authorship: Has the submitting author (@dominic-chang) made major contributions to the software? Does the full list of paper authors seem appropriate and complete?
• Substantial scholarly effort: Does this submission meet the scope eligibility described in the JOSS guidelines
• Data sharing: If the paper contains original data, data are accessible to the reviewers. If the paper contains no original data, please check this item.
• Reproducibility: If the paper contains original results, results are entirely reproducible by reviewers. If the paper contains no original results, please check this item.
• Human and animal research: If the paper contains original data research on humans subjects or animals, does it comply with JOSS's human participants research policy and/or animal research policy? If the paper contains no such data, please check this item.

Functionality

• Installation: Does installation proceed as outlined in the documentation?
• Functionality: Have the functional claims of the software been confirmed?
• Performance: If there are any performance claims of the software, have they been confirmed? (If there are no claims, please check off this item.)

Documentation

• A statement of need: Do the authors clearly state what problems the software is designed to solve and who the target audience is?
• Installation instructions: Is there a clearly-stated list of dependencies? Ideally these should be handled with an automated package management solution.
• Example usage: Do the authors include examples of how to use the software (ideally to solve real-world analysis problems).
• Functionality documentation: Is the core functionality of the software documented to a satisfactory level (e.g., API method documentation)?
• Automated tests: Are there automated tests or manual steps described so that the functionality of the software can be verified?
• Community guidelines: Are there clear guidelines for third parties wishing to 1) Contribute to the software 2) Report issues or problems with the software 3) Seek support

Software paper

• Summary: Has a clear description of the high-level functionality and purpose of the software for a diverse, non-specialist audience been provided?
• A statement of need: Does the paper have a section titled 'Statement of need' that clearly states what problems the software is designed to solve, who the target audience is, and its relation to other work?
• State of the field: Do the authors describe how this software compares to other commonly-used packages?
• Quality of writing: Is the paper well written (i.e., it does not require editing for structure, language, or writing quality)?
• References: Is the list of references complete, and is everything cited appropriately that should be cited (e.g., papers, datasets, software)? Do references in the text use the proper citation syntax?

[alejandroc137]

@lrnv, I do not have more comments. Please let me know if there is anything else to do

[lrnv]

@alejandroc137 Are your questions answered and requirements met by the author yet, or are you still waiting for responses / modifications / issues to be closed ? In the first case, maybe you could re-consider checking the boxes in this thread?

In both cases, you don't have much more to do, except maybe telling me briefly what did you think about the submission ?

[dominic-chang]

@lrnv I've made changes to the draft. Do you what command I should use to update the draft with the new version?

[lrnv]

@editorialbot generate pdf

[editorialbot]

👉📄 Download article proof 📄 View article proof on GitHub 📄 👈

[ExpandingMan]

I'm pretty much ready to sign off on this and finish up my involvement, but I'd like to address the following:

First, while I have been able to verify that the bulk of the code here is appropriate for use on GPU, and can be made to work, at time of writing I'm still struggling to produce straightforward examples of common use cases. I intend to work with the author (see here) and hopefully with my access to nvidia GPU's I can get it the last bit of the way to working smoothly on CUDA, but I think a more blindingly obvious GPU example is needed first.

Second, what are the expectations here as far as rigorous validation of the integrals? The math looks good to me, but there is of course a gaping chasm between reading the paper that derives the geodesic formulae with a cursory review of the code and a thorough and rigorous validation. The author seems to have done quite a good job with testing, but even carefully reviewing the tests I think will take some effort. The implementation requires quite a lot of subtlety as analytic solutions go because there is a bunch of branching and topology going on. My understanding is that expectations regarding these kinds of detailed and rigorous validations vary from field to field and journal to journal, so I wanted to get a feel for what those expectations would be here. (Btw, I suspect that maybe the authors of 1910.12881 have either informed or checked the work here? They would likely be far more capable of spotting issues than any of us.)

[dominic-chang]

On point 2:
Unfortunately, The development of this code happened independently from the authors of arXiv:1910.12881. I'm not even sure if they know this code exists. The code also implements some additional integrals that are outside the scope of the original paper, e.g. integrals associated with a regularization of the time integral for asymptotic observers. One thing I will say is that there are tests in the CI that check the analytic solutions by comparing them to numerical implementations of the integrals from the paper. See for example: @testset "Radial Integrals 1" begin. This way I can somewhat guarantee the solutions are correct, assuming that I copied down the integral expressions correctly.

[ExpandingMan]

All perfectly fair. I think you did everything you could have done here, it's just a matter of how much additional work are we all going to do to validate it. I kind of expect that with JOSS a sanity check is enough, and digging through the details to the point where I have as good a chance spotting a mistake as you do will take quite a lot of work, so I'm satisfied. I just wanted to make clear first that no, I have not stripped down and reconstructed the integral code to the point where I can personally vouch for its accuracy and second, to make sure we all have the same expectations. Again, short of doing a lot of work, everything looks good to me.

[alejandroc137]

The author has implemented all my comments and suggestions. This code and the applications are a great addition to our community. I echo one @ExpandingMan comment that it was hard to get easy examples of common use cases from the ones the author provided. However, the new examples are more commented on and have more parts that could serve as the building blocks for more applications.

I think the equations and implementation of the raytracing must be, for the most part, correct (a careful checking of them will be very time-consuming indeed). Suppose there are (significant) typos or these are incorrect. In that case, in my experience, they would already be manifest in the results: with these analytical expressions (which we also implemented in AART with my collaborators, including one of the authors of 1910.12881), when mainly considering ordinary geodesics (i.e., η >0), if there were extra/missing terms, sign errors, lots of nan will appear, as these functions are very sensible, and the geometry of the black hole extreme enough to saturate their bounds, and higher order rings will look "weird" and these errors will be apparent. The current implementation's novel part is how the time was normalized, and the results make physical sense in the regions I checked. At any rate, if there were any typos, the code can be easily fixed, and I am confident the author will certainly do so.

My last super minor comment to the manuscript is to change "... yet to be observed" to "...yet to be resolved" when talking about photon rings. As the author surely knows, the photons from these higher-order contributions do arrive at the radio telescopes, but the whole point of these types of efforts and future instruments is to understand them enough to resolve them!

[lrnv]

Yes @ExpandingMan you are right, the level of validation I can see here seem largely enough for this kind of review. After all, reviewers are not authors, and bugs are part of the life cycle of software. I would not be able to comment on the details though as I don't fully understand what is going on here, but you three seem to know what you are talking about.

@alejandroc137 Well received, thanks a lot for your input on this submission.

@dominic-chang, let us also wait to hear @aplavin oppinon

[editorialbot]

Hello @dominic-chang, here are the things you can ask me to do:

# List all available commands
@editorialbot commands

# Get a list of all editors's GitHub handles
@editorialbot list editors

# Adds a checklist for the reviewer using this command
@editorialbot generate my checklist

# Set a value for branch
@editorialbot set joss-paper as branch

# Run checks and provide information on the repository and the paper file
@editorialbot check repository

# Check the references of the paper for missing DOIs
@editorialbot check references

# Generates the pdf paper
@editorialbot generate pdf

# Generates a LaTeX preprint file
@editorialbot generate preprint

# Get a link to the complete list of reviewers
@editorialbot list reviewers

[dominic-chang]

@editorialbot generate pdf

[editorialbot]

👉📄 Download article proof 📄 View article proof on GitHub 📄 👈

[dominic-chang]

Completed tasks @lrnv

• Double check authors and affiliations (including ORCIDs)

Checked and Confirmed

• Make a release of the software with the latest changes from the review and post the version number here. This is the version that will be used in the JOSS paper.

Done. The version for the paper is v0.3.1

• Archive the release on Zenodo/figshare/etc and post the DOI here.

Done. Here is the doi 10.5281/zenodo.13936258

• Make sure that the title and author list (including ORCIDs) in the archive match those in the JOSS paper.

Checked

• Make sure that the license listed for the archive is the same as the software license.

Both Licenses have been set to the MIT license

[lrnv]

@editorialbot set 10.5281/zenodo.13936258 as archive

[editorialbot]

Done! archive is now 10.5281/zenodo.13936258

[lrnv]

@editorialbot set v0.3.1 as version

[editorialbot]

Done! version is now v0.3.1

[lrnv]

@editorialbot generate pdf

[lrnv]

@editorialbot check references

[editorialbot]

Reference check summary (note 'MISSING' DOIs are suggestions that need verification):

✅ OK DOIs

- 10.1137/141000671 is OK
- 10.1126/sciadv.aaz1310 is OK
- 10.3847/2041-8213/ab0ec7 is OK
- 10.3847/2041-8213/ab0c96 is OK
- 10.3847/2041-8213/ac6674 is OK
- 10.1103/PhysRevD.107.043030 is OK
- 10.3847/1538-4357/ac9ab7 is OK
- 10.5281/ZENODO.6471796 is OK

🟡 SKIP DOIs

- None

❌ MISSING DOIs

- 10.1117/12.3019437 may be a valid DOI for title: The Black Hole Explorer: Photon Ring Science, Dete...

❌ INVALID DOIs

- None

[editorialbot]

👉📄 Download article proof 📄 View article proof on GitHub 📄 👈

[lrnv]

@dominic-chang there seem to be a missing DOI, and the automatic check found a potential one, could you check if it is indeed the right doi (and then add it in the bib file) or if it's a false positive ? Then I'll recomand-accept and pass the hand to the TEiC for finalisation

[dominic-chang]

Great, thanks. I updated the bib file with the new doi in commit 44912ade1672ed7ec585c51c907423a0944f3667

[lrnv]

@editorialbot check references

[lrnv]

@editorialbot generate pdf

[editorialbot]

Reference check summary (note 'MISSING' DOIs are suggestions that need verification):

✅ OK DOIs

- 10.1137/141000671 is OK
- 10.1126/sciadv.aaz1310 is OK
- 10.3847/2041-8213/ab0ec7 is OK
- 10.3847/2041-8213/ab0c96 is OK
- 10.3847/2041-8213/ac6674 is OK
- 10.1117/12.3019437 is OK
- 10.1103/PhysRevD.107.043030 is OK
- 10.3847/1538-4357/ac9ab7 is OK
- 10.5281/ZENODO.6471796 is OK

🟡 SKIP DOIs

- None

❌ MISSING DOIs

- None

❌ INVALID DOIs

- None

[editorialbot]

👉📄 Download article proof 📄 View article proof on GitHub 📄 👈

[lrnv]

@editorialbot recommend-accept

[editorialbot]

Attempting dry run of processing paper acceptance...

[editorialbot]

Reference check summary (note 'MISSING' DOIs are suggestions that need verification):

✅ OK DOIs

- 10.1137/141000671 is OK
- 10.1126/sciadv.aaz1310 is OK
- 10.3847/2041-8213/ab0ec7 is OK
- 10.3847/2041-8213/ab0c96 is OK
- 10.3847/2041-8213/ac6674 is OK
- 10.1117/12.3019437 is OK
- 10.1103/PhysRevD.107.043030 is OK
- 10.3847/1538-4357/ac9ab7 is OK
- 10.5281/ZENODO.6471796 is OK

🟡 SKIP DOIs

- None

❌ MISSING DOIs

- None

❌ INVALID DOIs

- None

[editorialbot]

👋 @openjournals/aass-eics, this paper is ready to be accepted and published.

Check final proof 👉📄 Download article

If the paper PDF and the deposit XML files look good in openjournals/joss-papers#6016, then you can now move forward with accepting the submission by compiling again with the command @editorialbot accept

[dominic-chang]

Apologies for the changes again. I updated a sentence for clarity and added one more name to the acknowledgements.

dominic-chang/Krang.jl@7545652

[dominic-chang]

@editorialbot generate pdf

[editorialbot]

👉📄 Download article proof 📄 View article proof on GitHub 📄 👈

[dominic-chang]

@editorialbot accept

[editorialbot]

I'm sorry @dominic-chang, I'm afraid I can't do that. That's something only eics are allowed to do.

[dominic-chang]

Sorry, a bit confused about what I should do

[lrnv]

@dominic-chang Nothing ! We simply have to wait for the TEic to take the lead now, should take a few days max (depends on his/her bandwidth, which i do not control).

Please sit tight and wait a bit more :)