Dear FreeFEM Developer,

I try to solve the following eigenvalue problem using SLPEc parallelly.

The FE space for `[u, v, p]`

is

```
fespace Xh(Th, [P2, P2, P1]);
```

Note that the variables U and V are independent of spatial variables, so they can not be defined through `fespace`

.

I solve the eigenvalue using

```
EPSSolve(A, B, vectors = vec, values = val, ....);
```

**My question is that** U and V **are not defined in any finite element space, how can we compose** `vec`

in `vectors = vec`

?

It seems impossible. I checked all the SLEPc examples provided by FreeFEM (link), but I didn’t find similar cases.

Can we store the eigenvector in an array, just like this

For example:

`real[int, int] EigVec(Xh.ndof+2, num);`

where `num`

denotes the number of eigenvalues.

Then we get eigenvectors through

```
Xh [eu, ev, ep];
eu[] = EigVec[0:Xh.ndof-1][0];
```

where `eu`

denotes the leading eigenvector.