dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Anne Voigt wrote:
> Hello,
>
> I try to create a ffc-form of this formular:
>
> \int_\gamma \phi * dot(\nable \psi, n) ds
>
> This is what I did:
>
> element = FiniteElement("Lagrange", "triangle", 1)
>
> v = BasisFunction(element)
> u = BasisFunction(element)
> n= FacetNormal("triangle")
>
> a = v*dot(grad(u),n)*ds
>
> Now my problem: the generated class for the BilinearForm in the header
> file says does it depend on some dolfin::Function ans this is what I don
> not understand?! 

You need to pass the normal vector as a function. Take a look at the DG 
demos.

Garth


Here you can see what I mean:
> // DOLFIN wrappers
>
> #include <dolfin/Form.h>
>
> class Integration_RandBilinearForm : public dolfin::Form
> {
> public:
>
>   Integration_RandBilinearForm(dolfin::Function& w0) : dolfin::Form()
>   {
>     __coefficients.push_back(&w0);
>   }
>
>   /// Return UFC form
>   virtual const ufc::form& form() const
>   {
>     return __form;
>   }
>   
>   /// Return array of coefficients
>   virtual const dolfin::Array<dolfin::Function*>& coefficients() const
>   {
>     return __coefficients;
>   }
>
> private:
>
>   // UFC form
>   UFC_Integration_RandBilinearForm __form;
>
>   /// Array of coefficients
>   dolfin::Array<dolfin::Function*> __coefficients;
>
> }; 
>
> What is this function? 
>
> Thanks for your support
> Anne
>
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