平滑曲线（SIR模型与社交距离）

GeoGebra 命令及参数

1. OrthogonalLine((90, 0), xAxis) → t3
2. Point(t3) → SD_{3}
3. OrthogonalLine((60, 0), xAxis) → t2
4. Point(t2) → SD_{2}
5. OrthogonalLine((30, 0), xAxis) → t1
6. Point(t1) → SD_{1}
7. OrthogonalLine((0, 0), xAxis) → t0
8. Point(t0) → SD_{0}
9. Polynomial({SD_{0}, SD_{1}, SD_{2}, SD_{3}}) → SD
10. NSolveODE({S', I', R'}, 0, {S_{0}, I_{0}, R_{0}}, TimeSpan) → SIRt, SIRt_{2}, SIRt_{3}
11. Length(SIRt_{2}) → Ilen
12. OrthogonalLine((120, 0), xAxis) → t4
13. Point(t4) → SD_{4}
14. OrthogonalLine((150, 0), xAxis) → t5
15. Point(t5) → SD_{5}
16. OrthogonalLine((180, 0), xAxis) → t6
17. Point(t6) → SD_{6}
18. OrthogonalLine((0, ICUbeds), yAxis) → ICU
19. Textfield(Population) → PopulationInput
20. Textfield(I_{0}) → I_0Input
21. Textfield(R_{0}) → R_0Input
22. First(SIRt_{2}, Ilen) → It
23. FitPoly(It, 56) → Ipoly
24. Textfield(CriticalRate) → CriticalRateInput
25. Textfield(ICUbeds) → ICUbedsInput
26. SelectedIndex(CountryList) → SelectedCountry
27. Max(Ipoly, 0, TimeSpan) → ImaxP