title: Distance from Point To Line great circle function not working right.
body: <p>I need to get the distance from a lat/lng point to a line. Of course needs to follow the Great Circle.</p>
  
  <p>I found a great article on this at <a href="http://www.movable-type.co.uk/scripts/latlong.html" rel="nofollow noreferrer">http://www.movable-type.co.uk/scripts/latlong.html</a></p>
  
  <p>but the code is not working right. Either I am doing something wrong or there is something missing. Here is the function in question. See the link for the other functions if needed.</p>
  
  <pre><code>    var R = 3961.3
      LatLon.crossTrack = function(lat1, lon1, lat2, lon2, lat3, lon3) {
       var d13 = LatLon.distHaversine(lat1, lon1, lat3, lon3);
       var brng12 = LatLon.bearing(lat1, lon1, lat2, lon2);
       var brng13 = LatLon.bearing(lat1, lon1, lat3, lon3);
       var dXt = Math.asin(Math.sin(d13/R)*Math.sin(brng13-brng12)) * R;
       return dXt;
      } 
  </code></pre>
  
  <p>lat/lon1 = -94.127592, 41.81762</p>
  
  <p>lat/lon2 = -94.087257, 41.848202</p>
  
  <p>lat/lon3 = -94.046875, 41.791057</p>
  
  <p>This reports 0.865 miles. The actual distance is 4.29905 miles. </p>
  
  <p>Any clues as to how to fix this? I am not a mathematician, just a long in the tooth programmer.</p>