[aerosayan]

During the coarsening step of a multigrid method, we need to create a smaller grid out of the bigger one.
This gets easier to do when the no. of rows and columns are even (and most preferably a power of 2). Just dividing by 2 gets us the dimensions of the new coarsened grid.


What to do when the no. of rows and columns are odd?


I got the idea of just taking the middle row and column of the fine grid and pretend they're actually made of two rows and columns. So, the total no. of rows and columns become even, and we can simply copy over the middle column from the fine grid to the coarse grid. I expect that might create some issues in the preservation of the conserved variables.