庞加莱对连续运动的轨迹用一个截面(叫庞加莱截面)将其横截，那么根据轨迹在截面上穿过的情况，就可以简洁地判断运动的形态，由此所得图像叫庞加莱映像。(Poincare maps Poincare's trajectory of continuous motion to a cross section (called Poincare cross section). Then we can judge the shape of motion succinctly based on the cross