Question about BC

[caojinbo]

Thanks for the great py-pde work.
I have a question about parameters in bc. for example, the document says
bc_lower = {'value': 4} bc_upper = {'value': 2} bc = [bc_lower, bc_upper]
What do 'lower' and 'upper' mean here? I tested these bc in Laplace equation, and found that x lower and upper is 4 (left and right side), the y lower and upper is 2 (top and bottom).

The other parameter seems to work as expected
bc=[[bc_x_lower, bc_x_upper], [bc_y_lower, bc_y_upper]]

[david-zwicker]

Boundaries are always perpendicular to axes in py-pde. The lower and upper then refers to the orientation of the axis. For example, in a 3d Cartesian system, the lower boundary condition along the x-direction is the yz-plane with the lowest value of the x-coordinate, while the upper boundary is the yz-plane with a large value of x. I guess it would help to have a schematic drawing in the documentation, but I didn't find the time to include one, yet. If you could make a schematic drawing to explain the situation, I would be happy to include it!

[caojinbo]

Thank you. If you are OK, I do want to do something with the documentation. The module is very powerful and it derserves more visibility.

[david-zwicker]

Yes, definitely. Extending the documentation or adding examples are definitely welcomed! The best thing would be if you could clone the repository, extend the documentation, and create a pull request that I could include in the main branch.