[Positioning] Compute the error if Real is used

If the pseudo-algorithm Real is used, the distance error is computed for
the others algorithms.

owlps-positioning/src/positioning.cc

@@ -51,7 +51,11 @@ void Positioning::initialise_algorithms()
        i != algo_names.end() ; ++i)
     {
       if (*i == "Real")
-        algorithms.push_back(new RealPosition) ;
+        /* In order to compute the errors of the other algorithms,
+         * Real must be the first for each request, so we add it at
+         * the begining.
+         */
+        algorithms.insert(algorithms.begin(), new RealPosition) ;
 
       else if (*i == "FBCM")
         {
@@ -87,10 +91,23 @@ void Positioning::loop()
       if (! request)
         continue ;
 
+      Point3D real_position ;
+      bool compute_error = false ;
       ResultList results(&request) ;
       for (algo = algorithms.begin() ; algo != algorithms.end() ;
            ++algo)
-        results.add((*algo)->compute(request)) ;
+        {
+          Result res((*algo)->compute(request)) ;
+          if (compute_error)
+            res.compute_error(real_position) ;
+          else if ((*algo)->get_name() == "Real")
+            {
+              compute_error = true ;
+              real_position = res.get_position() ;
+            }
+          results.add(res) ;
+        }
+
       output.write(results) ;
     }
 }

owlps-positioning/src/realposition.hh

@@ -11,7 +11,7 @@
 class RealPosition: public PositioningAlgorithm
 {
 public:
-  RealPosition(void): PositioningAlgorithm("RealPosition") {}
+  RealPosition(void): PositioningAlgorithm("Real") {}
 
   Result compute(const Request &request) ;
 } ;