[PATCH] Add two new libraries to requirement list (deb)

[Dirk Hohndel]

On Thu, Jun 11, 2015 at 01:52:02PM -0700, Linus Torvalds wrote:
> On Thu, Jun 11, 2015 at 11:53 AM, Dirk Hohndel <dirk at hohndel.org> wrote:
> >
> > QtPositioning is new - I use that to quickly calculate distances between
> > GPS locations.
> 
> Umm. Is that the only thing you use it for?

Umm, right now, yet.

> Because if it is, it's kind of wasteful.
> 
> The thing is, you only care about distances when they are near each
> other, at which point the surface of the earth can pretty much be
> considered flat.
> 
> Which means that you can just calculate the distance in the
> north-south direction, which is trivial:
> 
>   earthradius * (difference in latitude in radians)
> 
> and the distance in east-west direction:
> 
>   earthradius * (difference in longitude in radians) * cos(latitude)
> 
> and then - because you can approximate all relevant distances as being
> euclidian - you just get the usual d = sqrt(x*x+y*y) and you're done.
> 
> No silly new libraries needed.

Ok, so I'm lazy. What else is new.

> Now, if we care about distances on a bigger scale, that would be
> different. But I guess the "distance" you are calculating is the one
> where you then compare it to "20m or less"?

Yes.

> Yeah, the earth really *is* flat at those kinds of scales. Unless you
> want to take wave height etc into account.

not really.

/C