Thomas Algorithm: I want to know how to specify the boundary conditions of Thomas Algorithm.

I want to know how to specify the boundary conditions of Thomas Algorithm. I came to know from "help thomas" that :

LEFT is the left boundary conditions

RIGHT is the right boundary conditions

LEFT and RIGHT should be arranged in the form [THETA DTHETA CONS]

THETA is the theta coefficient in the boundary condition

DTHETA is the d theta / d x coefficient in the boundary condition

CONS is the constants, if any, on the right-hand side, minding the sign

What if I have boundary conditions which are constants. For example left boundary condtion is "20" and right boundary condtion is "100". Can I write ???

LEFT = [0 0 20];

RIGHT = [0 0 100];

Is that theoretically correct?

[Walter Roberson]

Are you using https://www.mathworks.com/matlabcentral/fileexchange/38640-implementation-of-thomas-algorithm-mex ?

Answer 1

[Ege Keskin]

Are you using this to solve a heat transfer problem? If so, the boundary conditions are usually constant because the integration constants are derived from the boundary conditions.

[Yogi Patel]

Yeah, I know the boundary conditions are constant. But do you know how to write that constant value of boundary condition in Thomas algorithm?

[Walter Roberson]

How to write the boundary conditions is going to depend on the implementation you are using. I asked for clarification of that, but you did not respond. Mathworks does not provide a function named thomas .