added gif for results

Author: liminchen

9_reduced_DOF/readme.md

@@ -3,6 +3,8 @@
 A square falling onto the ground under gravity is simulated using neo-Hookean elasticity and implicit Euler time integration in the reduced solution space constructed via polynomial functions or modal-order reduction.
 Each time step is solved by minimizing the Incremental Potential with the projected Newton method.
 
+![results](results.gif)
+
 ## Dependencies
 ```
 pip install numpy scipy pygame