Difference between revisions of "Gylbert Algorithm"
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| − | [The Algorithm] gives a location within a 1°x1° spherical quadrilateral, relative to the quadrilateral's borders. The user picks whichever 1°x1° spherical quadrilateral which they are in. | + | [[The Algorithm]] gives a location within a 1°x1° spherical quadrilateral, relative to the quadrilateral's borders. The user picks whichever 1°x1° spherical quadrilateral which they are in. |
Some cities, such as [[Calgary]], Alberta, are cut into two or four parts by [[graticule]] boundaries. On the [[xkcd Blag]], Gylbert suggested[http://blag.xkcd.com/2008/05/21/geohashing/#comment-18571] that each week, Calgarians pick the location which is closest to ''exactly'' 51°N, 114°W, a spot in the center of the city. This effectively uses a graticule centered on 51°N, 114°W. | Some cities, such as [[Calgary]], Alberta, are cut into two or four parts by [[graticule]] boundaries. On the [[xkcd Blag]], Gylbert suggested[http://blag.xkcd.com/2008/05/21/geohashing/#comment-18571] that each week, Calgarians pick the location which is closest to ''exactly'' 51°N, 114°W, a spot in the center of the city. This effectively uses a graticule centered on 51°N, 114°W. | ||
Revision as of 01:22, 24 May 2008
The Algorithm gives a location within a 1°x1° spherical quadrilateral, relative to the quadrilateral's borders. The user picks whichever 1°x1° spherical quadrilateral which they are in.
Some cities, such as Calgary, Alberta, are cut into two or four parts by graticule boundaries. On the xkcd Blag, Gylbert suggested[1] that each week, Calgarians pick the location which is closest to exactly 51°N, 114°W, a spot in the center of the city. This effectively uses a graticule centered on 51°N, 114°W.
The Gylbert Algorithm is not equivalent to running the Algorithm hash on the shifted graticule, which would get you a fifth location different from all four surrounding locations. No-one is likely to be there.
The Gylbert Algorithm may be used at the discretion of individuals, because it does not change the target locations, merely picks one of them.
