I was trying to find a way to just get the matrix for a differential equation ( no integration/ bilinear form ). That is just the matrix of an expression containing various derivatives on some fespace.

I found some things like “int0d” and most recently “intall0d” which
sounds like what I’m looking for but it is not used anywhere.

I was going to add something like “intzed” for this purpose since I can’t find another way
to get there. Thanks. Just making some matricies from varf I think I mostly understand
what is going on and at least for P0 elements things look about right by inspection

I just wanted to get the matrix representing a discretized differential equation- not the
variaional integral . I was wondering if that had something to to with support for strong form.
Thanks.

Well, that is intermingled lol. I have a case I’m doing for learning but also a start
on a practical application. It is just diffusion but with a spatially varying diffusivity
that depends on the species concentations. In essence, it is like a two component
glue such as epoxy with one component circulating in an inert state activated
at a surface. When the activated hardener meets the flue, the diffusivity drops.

Right now I’m doing finite difference along the time axis . And yes I wanted to get
the depednence of the time derivatives on the contirbutors to the laplacian.
But, it should be independent of that. That is, you can get a matrix in
FEM right? Its just now you only support the weak form.

Thanks. yes this is just diffusion. If there is interest and I get most of the
junk code removed, I can post the code. I realized I may be able to do this
even with the integration, I’m sure its just something dumb I was missing.