On Wed, Jan 19, 2011 at 10:39:03AM -0000, Raphael Kruse wrote: > Question #141904 on DOLFIN changed: > https://answers.launchpad.net/dolfin/+question/141904 > > Status: Answered => Open > > Raphael Kruse is still having a problem: > Hi, > > thank you for your answer! > > Yes, you are right. The final integral is over a 2-dimensional domain, > while the trial and testfunctions are 1-dimensional. > > But I hoped one can calculate the desired matrix in a perhaps iterative > fashion. > Say we have q(x,y) = q(x -y) such that > > [Qu](x) = \int q(x - y) u(y) dy > > is nothing more but the convolution of q and u. > > Is it possible to represent [Qu](x) as function instance in Fenics for a > given trial function u such that > > L = Qu*v*dx > c = assemble(L) > > and c is the column of my desired matrix, which is related to my trial > function u?
I don't see how that would work. Your L (and c) would then be something that depends on x. We can only assemble numbers (scalars, vectors, matrices). Perhaps if you express your q as a sum of basis functions? Then one could translate the dependency on x into a dependency on an index so that the above would be assembled into a matrix? Then another trick or two might solve the problem... I'm not trying to be cryptic, but I don't have time to think this through in detail atm. -- Anders _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : [email protected] Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
