On 02/06/2012 06:09 PM, John Peterson wrote: > On Mon, Feb 6, 2012 at 3:24 PM, David Knezevic > <[email protected]> wrote: >> Hi all, >> >> I'd like to use a DG version of the Lagrange shape functions. This is >> pursued, for example, in the book "Nodal Discontinuous Galerkin Methods" >> by Hesthaven and Warburton. > What's the main motivation for using the Lagrange basis? Better > conditioning than monomials?
I'd like to compare to a Matlab DG code which uses (or will use) these L2_LAGRANGE basis functions. These basis functions are important in Matlab because with, say, MONOMIALs, you need to do an L^2 projection to represent f(u_h) in the FE space. The element loop to assemble the right-hand side for this projection appears to be a bottleneck in Matlab, especially if you have to do it every timestep. With L2_LAGRANGE you can do interpolation instead of projection. Also, yep, conditioning of L2_LAGRANGE will be better than MONOMIALs for the same order shape functions. But (L2_)LAGRANGE only goes up to cubic and the condition number for cubic MONOMIALs isn't too bad. Dave ------------------------------------------------------------------------------ Try before you buy = See our experts in action! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-dev2 _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
