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

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Yogi Patel on 3 Feb 2019
Commented: Walter Roberson on 3 Feb 2019
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?

1 Comment

Ege Keskin on 3 Feb 2019
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 on 3 Feb 2019
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 on 3 Feb 2019
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 .