title: Detecting whether a GPS coordinate falls within a polygon on a map
body: <p>As stated in the title, the goal is to have a way for detecting whether a given GPS coordinate falls inside a polygon or not.</p>
  
  <p>The polygon itself can be either convex or concave. It's defined as a set of edge vectors and a known point within that polygon. Each edge vector is further defined by four coordinates which are the <strong>latitudes and longitudes</strong> of respective tip points and a bearing relative to the starting point.</p>
  
  <p>There are a couple of questions similar to this one here on StackOverflow but they describe the solution only in general terms and for a 2D plane, whereas I am looking for an existing implementation that supports polygons defined by latitude/longitude pairs in <a href="http://en.wikipedia.org/wiki/WGS_84" rel="noreferrer">WGS 84</a>.</p>
  
  <p>What API-s or services are out there for doing such collision tests?</p>