Wikipedia:Peer review/Geodesics on an ellipsoid/archive1

Geodesics on an ellipsoid
This peer review discussion has been closed. I've listed this article for peer review because it's close to its final form. Feedback is asked for concerning:
 * the figures -- are they clear enough? Should the captions be expanded?
 * the depth of the coverage -- I've attempted to cover the main ideas so that someone with a mathematical bent can follow them. On the other hand, I don't give the series expansions typically used in computer programs for determining geodesics.  I consider this unnecessary detail and interested readers can look these up in the references.
 * the references -- I've included the important ones in the development of this subject.

Thanks, cffk (talk) 21:01, 22 September 2013 (UTC)


 * OK, I am going to review it. I have a peer review coming and they said this was sort of kharma, to do one for others.  I checked a few interesting ones (Stanford, Mutation) but the peer review prompters were not doing work on the article.  Heading off to read...71.127.137.171 (talk) 04:48, 6 October 2013 (UTC)

1. It has some of the attributes of a typical math article, in too much attention to logical rigor and too little to explanation to the reader. Who do you consider your audience? Ph.D. geometers? People who have taken calculus? People who have not? Really, it's all of them and you need to think how to reach them all. You can't satisfy everyone equally, but a really useful trick is to make things simple at the start and hard further on. That said, at least this is not one of those damned Lie group articles. Really...for a math article, it's readable...but math articles are shockingly unreadable (even for Ph.D. chemists and engineers).

2. the lead is the most important part. Make it clear for as much of an audience as you can. Again, it's better than some math articles, but you have some good chances to name drop the Earth, great circle, etc.

3. I assume that a geodesic of an ellipsoid is a great circle of a sphere (of the Earth). Put that up front. It's something people have heard about when they took navigation classes.

4. Are there any commercial or engineering applications of this topic? sattelites, geology, etc? If there is any kind of human interest...play it up.

5. Can we do spherical trigonometry instead of spheroidal (simpler word). Also, wikilink to it. and it used to be a class people took in school.

6. A nice explanatory graphic might be helpful here:  draw a table of 3 images left to right. Show a sphere (all axes same), a spheroid (one axis different, 2 same) and then an ellipsoid (all axes different). you can display it centered. The reader gets a quick understanding of the hard words.

6. I'm not crazy about the Harvard citations. I hate bugging you about something like that...but realize you are already with one hand behind the back trying to convey a technical topic to a general audience. Now you mess up the prose with all those speed bumps.

7. "See for example Hansen (1865, p. 69)." Cut this. A citation would be sufficient (ideally not Harvard).

8. Could you sex it up a little with some pictures of the major derivers? Like this picture of Cassini almost seems to be geometrical...



9. Wikilink Cassini

10. Try to write in the normal Wiki flow (rather than discussing papers in the text and linking to the citations with whole words, link to the people's articles and just use numbered citations).

Here's what you have (with all the bluelinks to papers):


 * For an ellipsoid of revolution, the characteristic constant defining the geodesic was found by Clairaut (1735) in application to Cassini's map projection for France. A systematic solution for the paths of geodesics was given by Legendre (1806) and Oriani (1806) (and subsequent papers in 1808 and 1810). The full solution for the direct problem (complete with computational tables and a worked out example) is given by Bessel (1825).

Instead write like this:


 * In 1735, Clairaut first defined the characteristic constant of an ellipsoid of revolution when he solved the problem in application to the astronomer Cassini's map of France. In 1806, Legendre and Oriani produced the systematic solution for the geodesic path. In 1825, Bessel published the full solution of the direct problem with computational tables and a worked out example.

Do you see the difference in the two approaches? In the first, we are describing the history of papers or even discussing the topic while referring to papers. In the second, we get a story of how PEOPLE solved problems over the years. Which do you think resonates more?

11. On the other hand, this is a nice para "Much of the early work on these problems was carried out by mathematicians—for example, Legendre, Bessel, and Gauss—who were also heavily involved in the practical aspects of surveying. Beginning in about 1830, the disciplines diverged, with those with an interest in geodesy concentrating on the practical aspects such as approximations suitable for field work, while mathematicians pursued the solution of geodesics on a triaxial ellipsoid, the analysis of the stability of closed geodesics, etc."

12. I'm not sure if a perpendicular to the meridian is same as a geodesic. The former sounds a lot like a rhumb line, not a great circle.

13. Redraw figure 1 so the geodesic (the line from A to B) is the only part in red. Make things CLEAR.

14. "This article concentrates on the problem on an ellipsoid of revolution (both oblate and prolate). The problem on a triaxial ellipsoid is covered near the end." Nice explanation, but I don't see how this explanation is followed out in the structure. Not like there is a heading for oblate, then prolate, then tri-ax. also, consider my comment before on showing the globes. The reader does not know oblate and prolate. maybe my mix of 3 could have 4 pictures now, with clarity that oblate and prolate are in same class of "2 same".

15. The green and blue of figure 18 are hard to distinguish. Redraw with greater contrast (by color choice or thicker lines, or a less dense grid).

16. I don't understand the swaths of grid and non-grid in the pictures further down.

17. Work on the applications section. Not just a bulleted list. give me a little more about what is developing. Show me how the article helps me make money, or avoid getting killed, or kill a commie with an ICBM, or get laid.

18. Any cultural allusions (even broadly, perhaps to ellipsoids)? What about Mission of Gravity?

71.127.137.171 (talk) 06:14, 6 October 2013 (UTC)


 * Thanks for the feedback. I have a bunch of corrections I have to make.  Then I'll try to address your concerns. cffk (talk) 19:50, 6 October 2013 (UTC)


 * I didn't mean to rip into you too hard or to be repetitive. Just trying to put enough out there so you get the very fundamental point.  The topic could be written (with a lot of work) in a way that gives the general reader at least a grasp of most of the topic before heading off to hard core math land.  Of course, if you just want to write a math "proof style" article to other math profs or graduate students, feel free.  There is a lot of that here and the mathies have de facto sort of protected that.  But I can't help further than and I doubt you get much interest in polishing that sort of piece.71.127.137.171 (talk) 18:43, 12 October 2013 (UTC)

I still have plans to update the article in the light of your comments. In particular, I'm planning on greatly expanding the lead so that the main points (esp. the connection to the great circle) and made before plunging into details. (I hope this article isn't quite as intimidating as the one of Geodesics.) You will note that I redid the figure on the triaxial grid. cffk (talk) 19:04, 12 October 2013 (UTC)


 * Thanks for heart in right place! 71.127.137.171 (talk) 19:48, 12 October 2013 (UTC)

I've expanded the lead considerably and added pictures of the principal players. cffk (talk) 21:57, 25 October 2013 (UTC)


 * Progress. Now cut 80% of the equations (you don't need to show all derivations).  Remember what Steven Hawkings's publisher said...69.255.27.249 (talk) 04:35, 27 October 2013 (UTC)