[upd] updating FGraphDiff example

Author: nosmokingsurfer

python_examples/FGraphDiff_2d.py

@@ -12,8 +12,8 @@
 print('node 1 id = ', n1, ' , node 2 id = ', n2)
 
 invCov = np.identity(3)
-graph.add_factor_1pose_2d(np.array([0,0,np.pi/4]),n1,1e6*invCov)
-graph.add_factor_2poses_2d(np.ones(3),n1,n2,invCov)
+graph.add_factor_1pose_2d_diff(np.array([0,0,np.pi/4]),n1,1e6*invCov)
+graph.add_factor_2poses_2d_diff(np.ones(3),n1,n2,invCov)
 
 for i in range(10):
     graph.solve(mrob.FGraphDiff_GN)