说明：  求系统的时域性能指标的函数，给定系统的数学模型，即可通过该函数计算系统的超调量、峰值时间、调整时间和上升时间，经测试非常好用。
(system for the time-domain performance of the function, given the mathematical model, This function can be calculated by the overshoot, the peak time, adjusting time and rise time, the test is very handy.)