Bug fix: adjust Matlab node index

We have to be consistent with function `adjust_n` in the same script.

Convert_Matlab/overlap_v6.py

@@ -65,7 +65,8 @@ if __name__ == "__main__":
 
         for j1 in range(n_dates):
             for i1, id_child_1 in enumerate(id_child[:n_eddies[j1], j1]):
-                n1 = (date_num[j1] - date_num[0]) * e_overestim + i1 + 1
+                n1 = (d_init + date_num[j1] - date_num[0]) * e_overestim + i1 \
+                    + 1
                 # id_child_1 may be an int, which means there is a single
                 # successor, or id_child_1 may be a numpy array, which means
                 # there are several successors.