Bruno, thanks a lot for the clarification. Now that I read the docu again, it also seems clear to me that one has to construct the matrix oneself.
The transfer representation contains the information on how to map a coarse grid dof to the fine grid. This can be transformed to a matrix of size (dof_handler_fine.n_dofs(), dof_handler_coarse.n_dofs()). Directly applying this matrix to a vector leaves a lot of zero entries (i.e. those vector entries that don't have a dof correspondence on the coarse grid). See the attached image. So we still need to interpolate between the coarse values in the fine space. The only interpolation function that I found that uses a transformation matrix was this one https://dealii.org/8.5.0/doxygen/deal.II/namespaceVectorTools.html#a5e3af70a47cedfaf361cf5c621e94e3d. When looking into the implementation of this function, the interpolation function expects a FullMatrix of size (dof_handler_fine.get_fe().dofs_per_cell, dof_handler_coarse.get_fe().dofs_per_cell), so it has to map the cell data of individual cells to each other. I don't think that the transfer representation matrix can provide this information. Do you know how to create the matrix needed by the interpolate function using the data of the transfer representation? If not, is there another way to interpolate using a transfer matrix? Thanks a lot for your help. Best, Ina -- 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]. For more options, visit https://groups.google.com/d/optout.
