Some questions about Matrix and Vectors

dolfinx
1

Hello, in DOLFINX, it seems like we users have more power on the matrix and vector of the linear system. But I’m confused about some lines of the codes in this demo https://github.com/FEniCS/dolfinx/blob/v0.6.0/python/dolfinx/fem/petsc.py#L680

WX20231005-155304

  1. It seems to me that from line 221-224, we have already assemble the matrix, then what the function fem::set_diagonal actually does?
  2. For the vectors, I suppose that we employ the function apply_lifting() to apply the boundary condition, then what is the point to use the function set_bc?

Thanks very much!

2

Refer to the DOLFINx documentation and PETSc documentation.

3

Thanks for replying.