From: Thorsten Jolitz <tjolitz@gmail.com>
To: help-gnu-emacs@gnu.org
Subject: Re: distance from Easter Island to Chile
Date: Sun, 20 Apr 2014 12:26:15 +0200 [thread overview]
Message-ID: <874n1onvp4.fsf@gmail.com> (raw)
In-Reply-To: 83mwfgfnl0.fsf@gnu.org
Eli Zaretskii <eliz@gnu.org> writes:
>> From: Barry Margolin <barmar@alum.mit.edu>
>> Date: Sun, 20 Apr 2014 03:01:36 -0400
>>
>> In article <mailman.19905.1397975330.10748.help-gnu-emacs@gnu.org>,
>> Eli Zaretskii <eliz@gnu.org> wrote:
>>
>> > This is inaccurate (Earth is not a sphere).
>>
>> How accurate does your input have to be for that to be a significant?
>> I.e. if you're calculating the distance between two cities, and each
>> city is 5 miles wide, the distance is +/- 10 miles depending on where in
>> the two cities you decide to get the coordinates from. So if the error
>> in the formula is 2 miles, it's less than the inaccuracy in the input,
>> so the formula should be good enough.
>
> No one said that these calculations are only for distances between
> large cities.
>
> Anyway, the error induced by assuming spherical Earth can be up to 1%,
> which is not insignificant when the distances are on the order of
> magnitude of many hundreds of kilometers (3757 km and 4301 km values
> were cited by the OP).
I think one of the two French guys who had the task to establish a
world-wide accepted meter unit as
,-------------------------------------------------------------------------
| 1/10,000,000 part of the quarter of a meridian, measurement (1795) by
| Delambre and Mechain (http://en.wikipedia.org/wiki/History_of_the_metre)
`-------------------------------------------------------------------------
figured this out the hard way and became a depressed alcoholic because
of an unexplainable 300m 'measurement-error' in his triangulations.
--
cheers,
Thorsten
next prev parent reply other threads:[~2014-04-20 10:26 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-20 0:03 distance from Easter Island to Chile Emanuel Berg
2014-04-20 3:55 ` Frank Stutzman
2014-04-20 15:14 ` Emanuel Berg
2014-04-20 22:39 ` giacomo.boffi
[not found] ` <mailman.19957.1398033917.10748.help-gnu-emacs@gnu.org>
2014-04-21 1:40 ` Emanuel Berg
2014-04-21 1:50 ` Emanuel Berg
2014-04-21 9:45 ` giacomo.boffi
[not found] ` <mailman.19981.1398073560.10748.help-gnu-emacs@gnu.org>
2014-04-21 10:35 ` Emanuel Berg
2014-04-21 10:50 ` Emanuel Berg
2014-04-23 2:49 ` Emanuel Berg
2014-04-21 2:16 ` Emanuel Berg
2014-04-20 4:44 ` Barry Margolin
2014-04-20 15:06 ` Emanuel Berg
2014-04-20 6:28 ` Eli Zaretskii
[not found] ` <mailman.19905.1397975330.10748.help-gnu-emacs@gnu.org>
2014-04-20 7:01 ` Barry Margolin
2014-04-20 7:48 ` Eli Zaretskii
2014-04-20 10:26 ` Thorsten Jolitz [this message]
2014-04-20 11:03 ` Eli Zaretskii
2014-04-20 15:22 ` Emanuel Berg
2014-04-21 6:04 ` Emanuel Berg
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