Finite difference method for solving non linear ode with boundary conditions

 With the help of your video on YouTube and some raises questions, I try to plot these nonlinear second-order differential equations solved by the finite difference method but unfortunately, I don't get it to help me look at it maybe there is an error on the boundary conditions theta(-1)=0; theta(1) = 0. Or on my problem.

Thanks

[Sulaymon Eshkabilov]

The equations can be solved via [for ... end] or [while ... end] loop coding.