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## Re: simple assemble questions

 From: Edouard Oudet Subject: Re: simple assemble questions Date: Sat, 19 Jun 2021 07:59:29 +0200 User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1

```Great!
Thanks a lot,
best.

On 6/18/21 8:52 PM, Yves Renard wrote:
```
```

Dear Edouard,

In your example, 'a' seems to be a data, so that it has to be declared

```
If you declare it as a variable, the matrix given by gf.asm will have some entries for the variable 'a'.
```
```
And concerning your second example, you can of course reference a matrix data. For instance for a 3x3 matrix field with
```

```
where VM is the vector of the values of the matrix field in each dof (and in the fortran order for the components of the matrices).
```
Best regards,

Yves

Le 18/06/2021 à 19:36, Edouard Oudet a écrit :
```
```Dear getfem users,

```
I am interested in computing the following fem matrices on a domain Omega for Lagrange elements of order k
```
1) ∫∂Ω (∇u.n) v  a dσ

```
where a is a vector of length the number of dof, u and v are test functions and n the normal. I tried the following steps
```
md = gf.Model("real")
md.set_variable('a', ones(nbdof))

faces = gf.Mesh.get(tmesh, 'outer_faces')
bregion_id = 1
tmesh.set_region(bregion_id, faces)

```
B = gf.asm('generic', mim, 2, 'Normal.Grad_Test_u * Test2_u. a', bregion_id, md)
```
Does it look correct?

2) ∫Ω (M ∇u) . ∇v dx

```
where again u and v are scalar functions and M a matrix field (defined for every dof). I had in mind to do something like
```

```
but I do not know how how to define the matrix field and how to manage its product with my gradients.
```

I apologize one again for these naive questions,

best

Edouard.

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```
```
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--
Edouard Oudet : http://www-ljk.imag.fr/membres/Edouard.Oudet/
IMAG - Bureau 164
700 avenue Centrale
38400 Saint Martin d'Hères
+33 (0)4 57 42 17 71  (office LJK)

```