the center of the world (was Re: Check out O'Reilly's Open Source Convention Highlights)

[Keith F. Woeltje]

Saw this on slashdot and thought of this thread. Here's what the Debian 
folks did. My trig is pretty rusty, so I'm not sure the method is correct.

http://people.debian.org/~edward/average/

digging-up-old-threads-to-put-off-real-work-a-few-minutes-longer-ly yours
 >K

Alex Martelli wrote:

> "Grant Griffin" <not.this at seebelow.org> wrote in message
> news:3B3B2DED.5303198A at seebelow.org...
>     ...
> 
>>Hey, who said anything about "world"?...
>>
> 
> Kernighan and Ritchie did (they were greeting it, I believe).
> 
> 
> 
>>But now that you mention it, the US Midwest *is* pretty centrally
>>located on a "world" basis.
>>
>>as-much-as-anything-else-on-this-sphere-<wink>-ly y'rs,
>>
> 
> An interesting exercise might be to define a *meaningful*
> "central location" -- one based on population distribution
> (or other geographical distributions of interest).
> 
> After all, since tunas are unlikely to attend a conference
> on technical computer issues (given that you can tune a
> filesystem, but you can't tuna fish), "weighting" the vast
> aquaceous parts of the (approximate) "sphere" equally to
> the populated landmass may be a fine exercise in geometry,
> but doesn't make much sense otherwise.  As soon as you want
> to move from pure geometry to some kind of geography, I
> think some demographic issues must arise.  Even without
> considering demographics, at least some account could be
> taken of land vs ocean and maybe of land with/without
> permanent ice covering.
> 
> Some data, ordered by-country, can easily be found for free
> on the web, http://www.worldbank.org/data/wdi2001/worldview.htm
> for example.  Latitudes and longitudes of cities in various
> countries are also easily available, e.g. at
> http://www.realestate3d.com/gps/world-latlong.htm.  We can
> get a first approximation for a distribution of world human
> population by assuming a country's population is divided
> equally among its major cities.  This will require some work
> and supervision because of varying formats etc in the files
> being used -- or is there somewhere on the net that already
> gives me in a single readable file a lot of data boiled down
> to triples (population, latitude, longitude)?  Anyway, once
> I do have such a file, I can presumably find the "center of
> the world" (approximate) -- the one point on the Earth's surface
> that minimizes population-weighted sum of great-circle distances
> to 'population centers'.  Of course I could get different
> centers by choosing different weighing factors (country GNP
> rather than country population, for example).
> 
> Hmmm, if the coordinates were on a plane, finding the weighed
> center would be trivial, but offhand I can't think of how to
> do it on a sphere's surface -- I guess there must be some way
> more suitable than just solving a generalized extremization
> problem -- can anybody suggest one...?
> 
> Of course, there are enough degrees of freedom in the outlined
> procedure that it can probably be used for my real purpose, i.e.,
> proving that the relevant "center of the world" is within easy
> walking distance from my home and thereby convincing the PS^H^H
> O'Reilly to hold their next conference somewhere that's highly
> convenient for me...
> 
> 
> Alex
> 
> 
> 
>