" Say, P=(Px,Py) is the point outside the domain, T=(Tx, Tx) the closest vertex at the boundary as computed above, and grad_T the gradient of the finite element function at T. Then I would compute the function value at P as f(P) = f(T) + grad_T[0]*(Px-Tx) + grad_T[1]*(Py-Ty). "
Let me clarify one last thing: The gradient (deriv. with regards to x and y) of the above extrapolation is given by [ grad_T[0]; grad_T[1] ]. Correct? -Math Am Fr., 9. Juni 2023 um 17:39 Uhr schrieb Wolfgang Bangerth < [email protected]>: > On 6/9/23 09:24, Mathieu wrote: > > > > To have a unique gradient, it would be better to not search for the > closest > > vertex, > > but rather to the closest point at the boundary, which may be a point at > the > > line connecting two vertices. > > Perhaps, but it is not clear to me that this would actually be more > accurate. > > > > But there is no straightforward way to obtain this point, right? > > At least, I did not find a functionality in the GridTools namespace, > which is > > probably the right place to look for. > > Correct. > Best > W. > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: [email protected] > www: http://www.math.colostate.edu/~bangerth/ > > > -- > The deal.II project is located at http://www.dealii.org/ > For mailing list/forum options, see > https://groups.google.com/d/forum/dealii?hl=en > --- > You received this message because you are subscribed to a topic in the > Google Groups "deal.II User Group" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/dealii/RmYuqy3_3FY/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/c2f8044a-7210-e087-3f79-17ad2093879a%40colostate.edu > . > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/CA%2BwBsdNz0B2NyDNiXsY8BAtvqYVFdmQappKApigvrW0fJJ6tPA%40mail.gmail.com.
