Using device long/lat

I'm planning to incorporate devices status update in a python script. One of the things that I want to check is of course location.

But right now I'm stuck in the planning because I don't now how to check long/lat in a radius.

I guess you could do It separately, first long and then lat, but I guess there is a simpler way?

One of the things the code will do is to serve as a check so that the phone doesn't trigger geofences (exiting) inadvertently.
Or is it an unsound idea?

Sorry for the delay, had saved your post to reply when I got home and, well, forgot. Anyway, I am not sure how most people would do a distance calculation - you might have a look at the iFindStuff plugin as I THINK it does a distance calculation, perhaps using Google? Perhaps Mike can answer a question or two regarding that.

Which reminds me, I got most of this setup as a status update so that I could work with Mike and integrate with that plugin; once that is done might be another option as opposed to doing it yourself...

Tanx for the answer I read your post when the plugin was updated but didn't really connect the dots at the time.
Now I understand a bit better what the integration with iFindstuff would bring.
I'll try that when that's possible, have it installed just to thinker with it.

In the meantime I will keep my self occupied trying to solve the calculations just for the fun of it.