More or less, yes, together with how I could get the "column" vector I would like to apply the matrix to. It is not a problem to do that in a FTDT-setting, but I do not know how to do that in a FEM-setting.
Am Montag, 22. Juli 2019 00:05:45 UTC+2 schrieb Wolfgang Bangerth: > > On 7/12/19 11:28 AM, 'Maxi Miller' via deal.II User Group wrote: > > It is difficult to write it as a single integral. The operation is > similar to > > the split-step fourier method, i.e. transforming the column vector f(r) > once using > > g(rho)=2\pi\int_0^\infty rf(r)J_0(2\pi\rho r)dr, > > multiplying it with a vector, and transforming it back using > > f(r) = 2\pi\int_0^\infty\rho g(\rho)J_0(2\pi\rho r)d\rho > > The operation is for radially symmetric systems, i.e. with z along the > x-axis, > > and r along the y-axis. When starting on the left border with f_0, i.e. > at > > position z = 0, doing the operation mentioned above gives the values for > the > > nodes at z = 1, when enumerating the nodes from 0 to n along the z axis, > and > > having equidistant nodes along the z-axis. Those integrals can be > replaced by > > a matrix-vector-multiplication, thus making it easier to implement > numerically. > > This makes sense -- every linear operator can be represented as a matrix. > So > yes, you can express the operation as a matrix, and of course you can > express > this matrix using the deal.II classes. > > But I'm not clear what your question is then. Are you asking how to build > this > matrix? > > Best > W. > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: bang...@colostate.edu > <javascript:> > 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 the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/c11c3cf6-4f75-4fb4-abfb-85f5f61c28ba%40googlegroups.com.
