For the initial boundary value problem of radioactive gas in the medium, its diffusion equation is a non-homogeneous second-order partial differential equation, which tends to be complicated by analytic method. The finite difference method is efficient with the physical image being more visual and distinct. After discrete equations are derived from the corresponding implicit finite difference scheme, select appropriate grid, and then, use MATLAB software programming realization of radioactive gas diffusion equation of finite difference solution, and plot. Finally, n...