传染病sis模型代码，用于求解常微分方程模型，带有人口结构(Code of SIS model for infectious diseases)

使用拟合残差及残差平方和原理，以人口增长模型为例，结合寻优算法——局部最优解的非线性曲线拟合(Using the principle of fitting residuals and residual sum of squares, this paper takes population growth model as an example, and combines the optimization algorithm, the nonlinear curve fitting of local