Two new fourth-order three-stage symplectic integrators are specifically designed for a family of Hamiltonian systems,such as the harmonic oscillator,mathematical pendulum and latticeφ4 model.When the nonintegrable latticeφ4 system is taken as a test model,numerical comparisons show that the new methods have a great advantage over the second-order Verlet symplectic integrators in the accuracy of energy,become explicitly better than the usual non-gradient fourth-order seven-stage symplectic integrator of Forest and Ruth,and are almost equivalent to a fourth-order seven-stage force gradient symplectic integrator of Chin.As the most important advantage,the new integrators are convenient for solving the variational equations of many Hamiltonian systems so as to save a great deal of the computational cost when scanning a lot of orbits for chaos.
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机译：两岸四地累犯制度比较研究——兼论中国内地累犯制度一体化之构想 =Comparative Study on Recidivism System in Hong Kong, Macao, Taiwan and China: Concurrently Discuss the Conception of Recidivism System Integration in Mainland China
