Re: How many views...
| От | Holger Klawitter |
|---|---|
| Тема | Re: How many views... |
| Дата | |
| Msg-id | 200411290915.29686.lists@klawitter.de обсуждение исходный текст |
| Ответ на | Re: How many views... ("Uwe C. Schroeder" <uwe@oss4u.com>) |
| Список | pgsql-general |
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Hi,
> .... where sqrt(pow((lat1 - lat2),2) + pow((long1 - long2),2)) >= 50
I assume that you dont want to deal with distances > 1000km?!
> of the records that aren't in question anyways. How do you come to the
> lat/long values for the max difference? Is there a general formula for
> that?
You can problably resort to simplified formulas like this:
latitude: 1 degree ~~ 111km
longitude: 1 degree ~~ 111km * cos( reference latitude )
> (I hated math all my life ;-) )
The whole thing is likely to get tough for you then ;-)
Mit freundlichem Gruß / With kind regards
Holger Klawitter
- --
lists <at> klawitter <dot> de
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