Talk:Bipolar coordinates

90° convention?

This:

The σ and τ isosurfaces intersect at two points, not one. The foci divide each σ-isosurface circle into a longer and shorter arc. By convention, the σ on these two arcs differ by 90°, i.e., σ_shorter = σ_longer + 90°; this convention breaks the degeneracy of the coordinate system.

doesn't seem right.

• The geometric interpretation in the second diagram requires that the σ on the two arcs differs by 180° not 90° (and the geometric interpretation seems consistent with the formulae for x and y).
• Distinguishing shorter from longer arcs rather than lower (y < 0) from upper results in two breaks in the coordinate system - an unlikely convention. A single 180°/-180° break between the poles or 0°/360° break on the x-axis not between the poles would be more plausible. --catslash (talk) 14:24, 22 November 2011 (UTC)

The third diagram suggests that σ_shorter = σ_longer. --catslash (talk) 00:22, 24 November 2011 (UTC)

• And it contradicts the sources [1] [2] (the diagrams in each case).

I shall delete this paragraph. --catslash (talk) 23:20, 4 December 2011 (UTC)

External links modified

Hello fellow Wikipedians,

I have just modified one external link on Bipolar coordinates. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

• Added archive https://web.archive.org/web/20071212005309/http://bbs.sachina.pku.edu.cn:80/Stat/Math_World/math/b/b233.htm to http://bbs.sachina.pku.edu.cn/Stat/Math_World/math/b/b233.htm

When you have finished reviewing my changes, please set the checked parameter below to true or failed to let others know (documentation at {{Sourcecheck}}).

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 5 June 2024).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 00:48, 3 November 2016 (UTC)