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Van
Constraint Violating Yak Guru
456 Posts |
 Posted - 11/06/2007 : 17:39:18
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| Oh yea, well what if "cat" really spelled dog... |
Edited by - Van on 11/06/2007 17:40:06 |
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Kristen
Test
United Kingdom
22191 Posts |
Posted - 11/06/2007 : 17:44:50
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| I didn't know that schrodinger's cat could spell "dog" ... |
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Van
Constraint Violating Yak Guru
456 Posts |
Posted - 11/06/2007 : 17:49:20
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| Actually it can't. It's not really a real cat but a theory. A hypothetical cat. But I guess hypotetically a cat could spell dog if it really wanted to. Better yet would be to see a cat operating a computer...I guess that would make it a Commodore PET. |
Edited by - Van on 11/06/2007 17:52:02 |
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Kristen
Test
United Kingdom
22191 Posts |
Posted - 11/07/2007 : 01:21:22
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"Commodore PET"
OMG ... You must feel as old as I am! |
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Kristen
Test
United Kingdom
22191 Posts |
Posted - 11/07/2007 : 02:10:13
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I have tried replacing
set @distance =
@radius * ( 2.0E *asin(case when 1.0E < @a then 1.0E else @a end ))
with
set @distance =
@radius * ( 2.0E * atn2(sqrt(@a), sqrt(1-@a)) )
that gives me a measurable variation in output values (looks lik 1% or 2%), but I still can't get the right values 
Kristen |
Edited by - Kristen on 11/07/2007 02:11:27 |
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Kristen
Test
United Kingdom
22191 Posts |
Posted - 11/07/2007 : 02:29:38
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Actually ignore that, I think it is accurate enough. Not sure whether ATN2 is more accurate than ASIN, I will report back on that point.
Kristen |
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SwePeso
Patron Saint of Lost Yaks
Sweden
29138 Posts |
Posted - 11/07/2007 : 03:31:42
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There is a formula that calculates the correct earth radius depending on latitude.
R' = a * (1 - e^2) / (1 - e^2 * sin^2(lat))^(3/2)
where a is the equatorial radius, b is the polar radius, and e is the eccentricity of the ellipsoid = (1 - b^2/a^2)^(1/2).
R' = a * (1 - (1 - b^2/a^2)) / (1 - (1 - b^2/a^2) * sin^2(lat))^(3/2)
E 12°55'05.25"
N 56°04'39.16" |
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Kristen
Test
United Kingdom
22191 Posts |
Posted - 11/07/2007 : 03:52:05
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| Wikipedia has radius 6356.78 km at the poles and 6378.14 km at the equator. |
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jezemine
Flowing Fount of Yak Knowledge
USA
2871 Posts |
Posted - 11/07/2007 : 08:46:55
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the eccentricity of the earth is gradually lessening because its rotation frequency is gradually decreasing, due to tidal forces from the earth-moon system. Eventually, in many billions of years, it will stop when the earth rotation and moon revolution are synchronized.
are you accounting for this?
elsasoft.org |
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spirit1
Cybernetic Yak Master
Slovenia
11741 Posts |
Posted - 11/07/2007 : 08:48:49
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and don't forget the reshifting of the earths weight due to global warming and ice melting. 
_______________________________________________
Causing trouble since 1980
blog: http://weblogs.sqlteam.com/mladenp
SSMS Add-in that does a few things: www.ssmstoolspack.com |
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Kristen
Test
United Kingdom
22191 Posts |
Posted - 11/07/2007 : 08:57:52
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| I've added a predictive algorithm to take into account asteroid impact. Given that the probability of being hit by an asteroid is about the same as being killed by an aircraft accident I thought it was an important addition. I allowed for a 20,000 mile detour pro-rata the probability of it happening ... |
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spirit1
Cybernetic Yak Master
Slovenia
11741 Posts |
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Kristen
Test
United Kingdom
22191 Posts |
Posted - 11/07/2007 : 09:36:07
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"what's your estimated asteroid size?"
Average .. from an asteroid's perspective ... |
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Michael Valentine Jones
Yak DBA Kernel (pronounced Colonel)
USA
6997 Posts |
Posted - 11/07/2007 : 09:36:31
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You have to consider the angle, mass, velocity and point of impact for the asteroid. If it hits on one side, it speeds up the Earth’s rotation, but on the other side it slows it down. Either will change the eccentricity of the earth, and change the error of the calculation.
CODO ERGO SUM |
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Van
Constraint Violating Yak Guru
456 Posts |
Posted - 11/07/2007 : 10:02:06
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| Hmmm. I remember playing Asteroids on my Commodore 64. |
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Zoroaster
Aged Yak Warrior
USA
702 Posts |
Posted - 11/07/2007 : 14:13:00
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Commodore 64, lucky .. I had a vic 20.
Future guru in the making. |
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jezemine
Flowing Fount of Yak Knowledge
USA
2871 Posts |
Posted - 11/07/2007 : 17:09:32
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quote:
Originally posted by Michael Valentine Jones
You have to consider the angle, mass, velocity and point of impact for the asteroid. If it hits on one side, it speeds up the Earth’s rotation, but on the other side it slows it down. Either will change the eccentricity of the earth, and change the error of the calculation.
CODO ERGO SUM
not to mention destroy the server where all of this is running. do you have a DR server on Mars?
elsasoft.org |
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Kristen
Test
United Kingdom
22191 Posts |
Posted - 11/08/2007 : 00:19:50
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"do you have a DR server on Mars?"
Ah ... that will be using the faster-than-light data replication my clients always seem to want. "No trouble Sir, just a little expense ..." |
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Ubbe
Starting Member
Sweden
14 Posts |
Posted - 01/07/2008 : 07:12:20
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Hello!
I think the Haversine formula distance calculation is excellent.
But can someone help a beginner to calculate the course between Start and Finish when i try to use Haversine formula.
ex. Stockholm -> London distance is 775 nm.
and i wish to no the course (Initial Heading) to the destinaion.
//ubbe
-oOo- |
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SwePeso
Patron Saint of Lost Yaks
Sweden
29138 Posts |
Posted - 01/07/2008 : 08:55:34
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You will have to use a database with all possible routes for that.
And then apply some kind of Dijkstra algorithm upon that.
E 12°55'05.25"
N 56°04'39.16" |
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Topic |
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Great Circle Distance Function - Haversine Formula
