________________________________
From: Martin Kronbichler <[email protected]>
To: Pietro Maximoff <[email protected]>
Cc: [email protected]
Sent: Monday, August 31, 2009 7:40:01 AM
Subject: Re: [deal.II] What to Use for the Solution Point
Dear Pietro,
> Ke = x * grad_phi_i * grad_phi_j
>
> with the integral sign of course and dx at the end.
>
> Whilst assembling the matrix, I need to multiply with x. How do I
> obtain this value.
By x you mean the spatial variable? By using
fe_values.get_quadrature_points()[q_point]
you get a Point<dim> of the position in real space of the quadrature point
q_point. To get a certain component, you can use the bracket operator [] with
argument 0,...,dim-1.
For this to work, you will need to add the flag update_quadrature_points
to the FEValues constructor.
Dear Martin
Thanks, that worked.
I wonder if you could also help me with these:
As I refine the mesh (1D), I'd need to scale the right-hand-side appropriately
as in that case, the solution would grow as 1/h. Do I do this by just dividing
the right-hand-side by 1/(2^refinement) ?
Also, how would I go about applying a non-homogeneous Neumann boundary
condition quickly at the right end?
I know that Step-7 shows an example but I was just wondering if there was a
simpler or another way.
Best regards
Pietro
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