added method to access isam2 results in incremental fixed lag smoother

gtsam_unstable/nonlinear/FixedLagSmoother.h

@@ -68,7 +68,6 @@ public:
     }
   };
 
-
   /** default constructor */
   FixedLagSmoother(double smootherLag = 0.0) : smootherLag_(smootherLag) { }
 

gtsam_unstable/nonlinear/IncrementalFixedLagSmoother.cpp

@@ -125,7 +125,7 @@ FixedLagSmoother::Result IncrementalFixedLagSmoother::update(
   KeyList additionalMarkedKeys(additionalKeys.begin(), additionalKeys.end());
 
   // Update iSAM2
-  ISAM2Result isamResult = isam_.update(newFactors, newTheta,
+  isamResult_ = isam_.update(newFactors, newTheta,
 		  factorToRemove, constrainedKeys, boost::none, additionalMarkedKeys);
 
   if (debug) {

gtsam_unstable/nonlinear/IncrementalFixedLagSmoother.h

@@ -109,11 +109,17 @@ public:
     return isam_.marginalCovariance(key);
   }
 
+  /// Get results of latest isam2 update
+  const ISAM2Result getISAM2Result() const{ return isamResult_; }
+
 protected:
   /** An iSAM2 object used to perform inference. The smoother lag is controlled
    * by what factors are removed each iteration */
   ISAM2 isam_;
 
+  /** Store results of latest isam2 update */
+  ISAM2Result isamResult_;
+
   /** Erase any keys associated with timestamps before the provided time */
   void eraseKeysBefore(double timestamp);