title: Determine if a GPS location is within a gpx track segment
body: <p>I have this .gpx file that is formatted as follows:</p>
  
  <pre><code>&lt;trk&gt;
  &lt;name&gt;Area1&lt;/name&gt;
  &lt;extensions&gt;
  &lt;gpxx:TrackExtension&gt;
  &lt;gpxx:DisplayColor&gt;Magenta&lt;/gpxx:DisplayColor&gt;
  &lt;/gpxx:TrackExtension&gt;
  &lt;/extensions&gt;
  &lt;trkseg&gt;
  &lt;trkpt lat="52.806521779700120" lon="5.795177063346190"/&gt;
  ...
  &lt;trkpt lat="52.806521779700120" lon="5.795177063346190"/&gt;
  &lt;/trkseg&gt;
  &lt;/trk&gt;
  &lt;trk&gt;
  &lt;name&gt;Area2&lt;/name&gt;
  &lt;extensions&gt;
  &lt;gpxx:TrackExtension&gt;
  &lt;gpxx:DisplayColor&gt;Magenta&lt;/gpxx:DisplayColor&gt;
  &lt;/gpxx:TrackExtension&gt;
  &lt;/extensions&gt;
  &lt;trkseg&gt;
  &lt;trkpt lat="52.764805147811629" lon="5.377259838276261"/&gt;
  ...
  </code></pre>
  
  <p>This file that contains well over 18.000 coordinates, describes several (adjacent) areas.</p>
  
  <p>My ultimate goal is to see, if a given GPS coordinate is within the borders of any of these areas. What would be the best approach for that?</p>
  
  <p>Related, intermediate question:
  Will any method be reasonable fast to run through all these coordinates?</p>