On Tue, Jan 18, 2011 at 12:47:22PM -0000, Raphael Kruse wrote: > New question #141904 on DOLFIN: > https://answers.launchpad.net/dolfin/+question/141904 > > Hi, > > I am looking for a way to implement an integral operator in Python/Dolfin of > the following form: > > Carleman operator Q : L^2 -> L^2 > Given: an integral kernel q(x,y), where q is symmetric q(x,y) = q(y,x) > > For u in L^2 the integral operator Q is given by > [Qu](x) = \int q(x,y) u(y) dy > > In particular, I am interested in determing the eigenvalues and > eigenfunctions of Q, i.e. > > Qu = \lambda u > > Thus, for a finite element approximation I need the matrix > > \int \int q(x,y) u(x) v(y) dy dx > > where u and v are the trial and test function, respectively. > > I am new to Dolfin and sorry if there already is an answer to this question. > > Thank you for any help!
I don't think this is possible. As I understand you want 1-dimensional trial and test functions and integrate that over a 2-dimensional domain. DOLFIN assumes that everything you integrate has the same dimension as the domain. One inefficient way to do this would be to use 2-dimensional trial and test functions and then sum appropriately over the columns and rows of the matrix to reduce to 1-dimensional. I haven't thought it through in detail but it should be possible. -- Anders _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : dolfin@lists.launchpad.net Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
