> I'm not sure if I'm making sense here. Both of you suggested using > assemble which requires Form which, if I'm not wrong, requires > Function and that needs FunctionSpace which requires Mesh, but I > emphasised that this is no FEM problem :) I'm just trying to get the > best of available LA in dolfin. > > Let me give you a concrete example, have a look at Eq 12 of this paper: > > http://www.mia.uni-saarland.de/Publications/brox-eccv04-of.pdf > > Is it possible to use assemble() to extract A and b out of this > equation? Many of the coefficients in the equation are image data, I > guess I should convert the image data to Matrix and use Variable for > the unknowns?
In Dolfin we use FEM. The assemble function turns a variational form into a matrix, a vector or a number depending on the form. Kent > > > -Ali > > 2009/2/25 <[email protected]>: >> >> I'm not exactly sure what you are asking. But it is easy to obtain the >> matrices >> and vectors in the linear system to be solved. >> >> eg. >> dolfin/demo/la/trilinos/python/demo.py >> >> shows how to solve the system using Trilinos. You can use dolfin >> to make matrices and vectors in PETSc, uBlas, MTL, and Trilinos format. >> You can choose to let dolfin solve it for you or you can get the >> underlying >> matrix and solve it with the above LA libraries. >> >> Kent >> >> >> >>> Is the linear algebra support in dolfin capable of automatically >>> generating the sparse linear system of equations? (I know that ffc >>> effectively does this, but note that this question does not involve >>> solving a PDE using FEM, but a linear system of equations). >>> >>> For example, assume we have some busy sets of linear equations and we >>> wish to convert them to Ax = b so that we can feed them to the linear >>> solvers. Is there any way of automatically obtaining A and b avoiding >>> manual calculations and hard-coding? >>> >>> >>> -Ali >>> _______________________________________________ >>> DOLFIN-dev mailing list >>> [email protected] >>> http://www.fenics.org/mailman/listinfo/dolfin-dev >>> >> >> >> > _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
