Discrete symmetrical perturbation and variational algorithm of disturbed Lagrangian systems<xref rid="cpb_28_3_030201fn1" ref-type="fn">*</xref><fn id="cpb_28_3_030201fn1"><label>*</label><p>Project supported by the National Natural Science Foundation of China (Grant No. 11502071) and the Special Research Project of Beijing Information Science and Technology University, China.</p></fn>

Discrete symmetrical perturbation and variational algorithm of disturbed Lagrangian systems**

Project supported by the National Natural Science Foundation of China (Grant No. 11502071) and the Special Research Project of Beijing Information Science and Technology University, China.

Xia Li-Li¹, Ge Xin-Sheng², Chen Li-Qun^{3, †}

Error in the energy for free harmonic oscillator versus time.