• Billiard example
• Three-body example
• Stiffness-Aware Index (SAI) and Stiffness Index (SI)

For the figures in the first three columns, the solid curves represet the reference orbits and the dotted curves are the orbits simulated by learned Hamiltonian. The figures in the last column show the system energy.

The color markers (e.g. the purple squares, cyan triangles and black pentagons) represent the occurrence of the stiffness phenomena. The trend of SI and SAI are consistent.