to formulate this better... I need to get the matrix operator that links the local nodal and modal DG approximations on an arbitrary element (the Vandermonde-like matrix). Is this already implemented somewhere in deal.ii, or would I be better off just coding it by hand?
Many thanks! ----- Weitergeleitete Mail ---- Von: mihai alexe <[email protected]> Gesendet: Donnerstag, den 17. Februar 2011, 18:23:29 Uhr Betreff: getting local expansion coefficients from (nodal) dof values Hello all, this question may have arisen before... but how can one get (using deal.ii) from the discrete solution vector (essentially the numerical solution values at the DoF points for my DG implementation) the expansion coefficients for the solution on each element? That is, I want c_i for each active cell k, where u(x) |_k = \sum_i c_i \Psi_i(x) and Psi_i(x) are the canonical functions of the local Lagrange basis. I know this amounts to multiplication to a Vandermonde-like interpolation matrix, but I was wondering if there is some automatic support for this in deal.ii. if I am making some wrong assumptions on how deal.ii stores the numerical solution (say, in step-12 or step-39), please let me know. thank you! -- Mihai
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