diff --git a/matlab/unstable_examples/+imuSimulator/covarianceAnalysisBetween.m b/matlab/unstable_examples/+imuSimulator/covarianceAnalysisBetween.m
index 5768a068b..3b2486160 100644
--- a/matlab/unstable_examples/+imuSimulator/covarianceAnalysisBetween.m
+++ b/matlab/unstable_examples/+imuSimulator/covarianceAnalysisBetween.m
@@ -21,9 +21,11 @@ options.includeIMUFactors = 1;     % if true, IMU factors will be added between
 options.imuFactorType = 1;         % Set to 1 or 2 to use IMU type 1 or type 2 factors (will default to type 1)
 options.imuNonzeroBias = 0;        % if true, a nonzero bias is applied to IMU measurements
 
-options.includeCameraFactors = 0;  % not fully implemented yet
+options.includeCameraFactors = 0;  % not fully implementemeasurements, values, noiseModels, measurementNoise, options, metadatad yet
 numberOfLandmarks = 10;            % Total number of visual landmarks, used for camera factors
 
+options.includeGPSFactors = 0;     % if true, GPS factors will be added as priors to poses
+
 options.trajectoryLength = 209;    % length of the ground truth trajectory
 options.subsampleStep = 20;        % number of poses to skip when using real data (to reduce computation on long trajectories)
 
diff --git a/matlab/unstable_examples/+imuSimulator/covarianceAnalysisCreateFactorGraph.m b/matlab/unstable_examples/+imuSimulator/covarianceAnalysisCreateFactorGraph.m
index 094dd10b2..396a5a4eb 100644
--- a/matlab/unstable_examples/+imuSimulator/covarianceAnalysisCreateFactorGraph.m
+++ b/matlab/unstable_examples/+imuSimulator/covarianceAnalysisCreateFactorGraph.m
@@ -145,6 +145,13 @@ for i=0:length(measurements)
       %fprintf('(Pose %d) %d landmarks behind the camera\n', i, numSkipped);
     end % end of Camera factor creation
     
+    %% Add GPS factors
+    if options.includeGPSFactors == 1
+      currentGPSKey = symbol('g', i);
+      graph.add(GPSPriorFactor(currentPoseKey, measurements(i).gpsPosition, ...
+          noiseModel.Isotropic.Sigma(3, 1e-4)));
+    end % end of GPS factor creation
+    
   end % end of else (i=0)
   
 end % end of for over trajectory
diff --git a/matlab/unstable_examples/+imuSimulator/covarianceAnalysisCreateTrajectory.m b/matlab/unstable_examples/+imuSimulator/covarianceAnalysisCreateTrajectory.m
index cce0f69ee..e895fb8a6 100644
--- a/matlab/unstable_examples/+imuSimulator/covarianceAnalysisCreateTrajectory.m
+++ b/matlab/unstable_examples/+imuSimulator/covarianceAnalysisCreateTrajectory.m
@@ -24,7 +24,7 @@ if options.useRealData == 1
   for i=0:options.trajectoryLength
     scenarioInd = options.subsampleStep * i + 1;
     fprintf('%d, ', scenarioInd);
-    if (mod(i,20) == 0) fprintf('\n'); end
+    if (mod(i,12) == 0) fprintf('\n'); end
     
     %% Generate the current pose
     currentPoseKey = symbol('x', i);
@@ -80,6 +80,12 @@ if options.useRealData == 1
       values.insert(currentBiasKey, metadata.imu.zeroBias);
     end
     
+    %% gt GPS measurements
+    if options.includeGPSFactors == 1 && i > 0
+      gpsPosition = imuSimulator.getPoseFromGtScenario(gtScenario,scenarioInd).translation.vector;
+      measurements(i).gpsPosition = Point3(gpsPosition);
+    end
+    
   end
   fprintf('\n');
 else