Talk:Haversine formula

message: I undid the change from cos to sin. Cos is correct when the formula is expressed in terms of latitude.
NB in the general haversine formula given below under "law of haversines" for a spherical triangle sin is indeed correct.
The point is simply that latitude is measured from the equator not the pole, so sin of the great-circle distance from the pole becomes cos(latitude).  — Preceding unsigned comment added by Dgwsoft (talk • contribs) 11:51, 14 September 2011 (UTC)
thread_title: Cos or sin in the first formula?

message: Hi. I've put up a possible rearrangement of the whole article at Talk:Haversine_formula/Alt
Some points about it:
*The main goal was to arrange the article so that the novice outsider, upon clicking to it, could get a quick summary of the haversine formula as quickly and painlessly as possible.
*All discussions about the technical aspects and rationale are moved to the second section, the first paragraph of which is intended for the general reader. The rest of the section (which I haven't presumed to write) would be more technical in nature, and could perhaps be in smaller type to make this distinction clear.
*I've left the remainder of the article unchanged.
Comments? If you like this ordering, please work on that second section (beyond the first paragraph) so that there's a logical progression! Thanks— Doops 03:14, 15 Apr 2004 (UTC)
thread_title: Possible rearrangement

message: The article states, that haversine is not 100% accurate for the planet earth due to the
fact that it's an ellipsoid.
couldn't the article link to an entry with the correct formula or at least the name of the formula to be used for the earth?  —Preceding unsigned comment added by 81.56.82.123 (talk) 00:29, 19 August 2008 (UTC)
thread_title:  Suggestion to add the precise formula for the earth 

message: Just in case anybody is tempted to do a straight computer implementation of the haversine formula, with its large numerical errors near the antipodal point, maybe it could be useful to add a mention of another algorithm by William Kahan that addresses that issue?
His somewhat roundabout description is at 
http://www.cs.berkeley.edu/~wkahan/Math128/angle.pdf
Terry0051 (talk) 23:29, 2 March 2009 (UTC)
replies: text: Discussion of alternative formulas for great-circle distances belongs on Great-circle distance, not here.  —Steven G. Johnson (talk) 02:45, 3 March 2009 (UTC)
replies: text: It's certainly surprising if a discussion of the material in this very article belongs only somewhere else: the formula previously mentioned is effectively a recasting of the formula that is the subject of this article, providing the same result while avoiding the numerical drawback.Terry0051 (talk) 16:47, 4 March 2009 (UTC)
replies: text: All great-circle formulas are a recasting of the haversine formula, because all of them are equivalent in exact arithmetic.  We have a whole article on great-circle formulas; we shouldn't be duplicating that material here when we can just link to that article.  —Steven G. Johnson (talk) 17:30, 4 March 2009 (UTC)
thread_title: Useful to add mention of Kahan's formula?

message: The article suggests using the geometric mean of the earth's equatorial and polar radii.  There are two problems with this:  First, it matters very little which mean is used for two numbers so close in value.  The difference between the geometric and arithmetic means is only about 9 meters.  But using either unweighted mean ignores the fact that much of the earth's surface is closer to the equator than to the poles.  The average over the entire surface is about 2/3 a + 1/3 b, where a is the equatorial radius and b the polar radius, or a(1-1/3f), where f is the flattening.  Using the WGS84 numbers, this is 6371008.771 meters, which for all practical purposes can be rounded to 6371 kilometers.  —Preceding unsigned comment added by 63.86.92.198 (talk) 13:25, 6 May 2009 (UTC)
thread_title:  Geometric mean? 

message: There are no factors of Pi in the equation so it should work perfectly well if your latitude and longitude are in degrees. Just don't mix radians and degrees in the same sin or cos.
:Probably the "in radians" was because the formula also includes haversine(d/R), which is only correct if the argument to the haversine function is taken to be in radians.  — Steven G. Johnson (talk) 04:02, 5 August 2009 (UTC)
thread_title: Why not delete the "(in radians)" part

message: If I have two points defined as Lat1, Long1 and Lat2 and Long2, where these numbers are in terms of degrees of latitude and longitude (in terms of decimal degrees, not DMS) then how would I use the Haversine forumula to compute the distance between the two points, and the angle (or heading) of point 2 relative to point 1.  For example, if the first point was the location of my TV antenna, and the second point was the location of a TV transmission tower (50 to 150 miles away), then I want to know the distance and also the direction to point my antenna.  (I know that TV fool.com does this, but I want to compute the heading or direction manually).  — Preceding unsigned comment added by 65.95.198.181 (talk) 16:58, 25 May 2013 (UTC)
thread_title:  How to use Haversine to compute distance and angle between two points? 

message: It would be nice if Wikipedia could have a formula for distances on ellipsoids, e.g. the WGS84 ellipsoid (prefererably a generic formula with parameters for WGS84 and other geodetic ellipsoids). If Wiki already has such an article this article should link to it.150.227.15.253 (talk) 14:37, 21 February 2019 (UTC)
replies: text: Have you seen geodesics on an ellipsoid? Also see . –jacobolus (t) 03:26, 9 May 2023 (UTC)
thread_title:  Ellipsoid distances