Crank Nicolson method with convective and insulated boundary conditions

Hi!

For one dimensional heat diffusion with Crank Nicolson method, I had trouble writing a code for convective boundary condition at x=L and insulated boundary condition at x=0.

I would really appreciate it if you can help me with these 2 boundary condition codes.

Thank you in advance!

[Mahyar Taghizade]

This is the code for my boundary conditions.

and this is the error I get:

Answer 1

[Alok Kumar]

leaving -u(n+1,k); shift all other variables to the right hand side of the equals sign

-u(n+1,k)= -u(n,k) -w.*u(n,k)+w.*q;