[ https://issues.apache.org/jira/browse/SIS45?page=com.atlassian.jira.plugin.system.issuetabpanels:alltabpanel
]
Chris A. Mattmann updated SIS45:

Component/s: distance functions
Fix Version/s: 0.3incubating
> Performance improvement of queryByPointRadius
> 
>
> Key: SIS45
> URL: https://issues.apache.org/jira/browse/SIS45
> Project: Spatial Information Systems
> Issue Type: Improvement
> Components: distance functions
> Reporter: Peter Karich
> Assignee: Chris A. Mattmann
> Fix For: 0.3incubating
>
>
> If I didn't make a mistake a search with the normal distance method took ~2.4s and with
this distance method it takes only about 0.7s:
> {code}
> public static double getHaversineDistance(double fromLat, double fromLon, double toLat,
double toLon) {
> double dLat = Math.toRadians(toLat  fromLat);
> double dLon = Math.toRadians(toLon  fromLon);
> double a = Math.sin(dLat / 2) * Math.sin(dLat / 2)
> + Math.cos(Math.toRadians(fromLat)) * Math.cos(Math.toRadians(toLat))
* Math.sin(dLon / 2) * Math.sin(dLon / 2);
> return EARTH_RADIUS * 2 * Math.asin(Math.sqrt(a));
> }
> {code}
> Also one should think about normalizing the distance before the search so that one does
not need the whole last line which should give further speed improvements.
> I'm still unsure why it takes roughly the same time in my example for 10km, 20km and
40kmm where at every step a lot more nodes are involved. Normally I would say the mode nodes
 the more comparisons it'll take and the slower it should get. But it doesn't. Probably I'm
measuring wrong?

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