[petsc-users] [petsc-maint] How to impose boundary conditions using DMDA

[Lawrence Mitchell]

> On 29 Oct 2018, at 10:56, Matthew Knepley <knepley at gmail.com> wrote:
> 
> You can certainly map the right edge to the top edge (its topologically a square again), but that
> mapping is not smooth, and I do not know how you would make a global basis for the approximation space.

Yeah, I thought this was topologically just a cone, but that would have:

u(x=1) = -v(y=1)

and

v(x=1) = u(y=1) (note matching sign).

So if you wanted the v(x=1) = -u(y=1) there would be a twist somehow, and then a discontinuity in the mapping.

Lawrence