参考彭成荣《航天 总体设计》8.2.2节 使 Matlab绘制卫星星下点轨迹 1.地球静 轨道卫星，倾 分别为0，30，90度。(Referring to Peng Chengrong's total space design 8.2.2 section, Matlab draws the satellite orbit below the 1. satellite, which is 0, 30 and 90 degrees respectively.)

广义S变换，用于时频分析，是S的改进形式(Generalized S-transform, used in time-frequency analysis, is an improved form of S)