Thanks, Prof @frederichecht Sir,

And sorry for such an elementary question or for a wrong projection.

I am searching for a solution for an elliptic interface problem that includes two sub-domains:

I have to define FE space for \Omega_1, \Omega_2 and on interface \Gamma which I did like:

```
fespace Vh1(Th1, P1); // for domain1
fespace Vh2(Th2, P2); // for domain2
Vh1 u1, v1, lambda;
Vh2 u2, v2;
```

for defining a weak form on interface \Gamma I have restricted the weak formulation as:

```
int1d(Th1, interface)( lambda * v1 )
```

I am not sure about it;

Kindly comment to sort out this issue.

your comments/suggestions would help me to figure out such interface boundary problems.

or, any relevant source code that can handle such interface boundary problems.

Thanks Sir