At 01:46 PM 5/27/03 -0700, you wrote:
Micael,
Thanks for your input. My problem is limited to how far one is willing to travel to provide a service. The way I have it setup now is one can specify up to five locations (cities). But if someone wants to provide service to more than five cities they have no way of specifiying this. It is a bit more cumbersome to specify individual cities. On the other hand specifying a distance would require immediate feedback to the person providing the service so they can realize what cities they have specified (through distance). Another problem is a city that is included in the distance may want to be excluded. A solution that comes to mind is to allow the user to enter the number of cities they want to provide service in. But what is reasonable. 5, 10,100. That would be a pain in the neck to enter and may utilize an unnecessary amount of the database (would allow random cities not located adjacent to each other).
Barry
----- Original Message ----- From: "Micael" <[EMAIL PROTECTED]> To: "Struts Users Mailing List" <[EMAIL PROTECTED]> Sent: Friday, May 23, 2003 5:20 PM Subject: Re: [OT] Calculating distance using Longitude/Latitude
> Part of the answer is inevitably tied to your problem. If it is one kind > of a problem, then distance is crucial. If it is another, then popluation > is critical. Ten miles to a hotel in N.Y. is not ten miles to a hotel in > the Mojave Desert. Know what I mean? Usually people approach these > problems as distance problems when the actual area in which such solutions > will usually be employed make them into topographical problems. I am not > sure if that is relevant to you. If not, sorry for bothering you. Micael > > At 05:11 PM 5/23/03 -0700, you wrote: > >At 16:10 -0700 5/23/03, Barry Volpe spoke thusly: > > > >>Hi, > >> > >>I don't know if there is anything particular to struts on this subject.... > >> > >>What I want to do: > >> > >>I have a geo database with city,state and corresponding longitude,lattitude. > >>I want to allow a specific city/state location to be specified and a > >>distance to > >>be selected. Then all locations (in my database) within that distance > >>(square miles I guess) > >>can be displayed. > >The equations, for the simple assumptions (see below) do not require more > >then 10 lines of Java. You'd spend more time finding an implementation > >than just coding you equations. > > > >The simple assumption is to compute a box around the source location with > >sides equal to half the allowed distance. This will give you a min and max > >long and latitude that you could query against. Theoretically you should > >check against a circle around your source point, so this will include too > >many results in the query output. If you really need precision, you could > >also computed the square inscribed within the circle and if query results > >are inside the outer box, but outside the inner box, you could run > >additional filtering in Java do to the precise calculation. > >Off course the earth is not flat and the larger the distance, the more > >error is introduced. Also, the circle above, is not really a circle for > >the same reason. A possible modification is to compute the width of the > >box (longitude) based on the latitude closest to the equator. This would > >compensate for locations further away from the equator, but is still not > >100% precise. > >The trick, in the absence of even smarter approaches, is to do the quick > >math such that it includes at least all known good answers, so you can do > >some more filtering in code if necessary. > > > >--dolf > > > >--------------------------------------------------------------------- > >To unsubscribe, e-mail: [EMAIL PROTECTED] > >For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > LEGAL NOTICE > > This electronic mail transmission and any accompanying documents contain > information belonging to the sender which may be confidential and legally > privileged. This information is intended only for the use of the > individual or entity to whom this electronic mail transmission was sent as > indicated above. If you are not the intended recipient, any disclosure, > copying, distribution, or action taken in reliance on the contents of the > information contained in this transmission is strictly prohibited. If you > have received this transmission in error, please delete the message. Thank > you > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > > >
--------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
LEGAL NOTICE
This electronic mail transmission and any accompanying documents contain information belonging to the sender which may be confidential and legally privileged. This information is intended only for the use of the individual or entity to whom this electronic mail transmission was sent as indicated above. If you are not the intended recipient, any disclosure, copying, distribution, or action taken in reliance on the contents of the information contained in this transmission is strictly prohibited. If you have received this transmission in error, please delete the message. Thank you
--------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
