# Just Launched: You can now import projects and releases from Google Code onto SourceForge

We are excited to release new functionality to enable a 1-click import from Google Code onto the Allura platform on SourceForge. You can import tickets, wikis, source, releases, and more with a few simple steps.

## libmesh-users

 [Libmesh-users] Multi-Load case with periodic boundary condition From: Shengli Xu - 2007-05-23 02:35:03 Attachments: Message as HTML ```Dear Libmesh users, I want to solve the multi-load case problem with periodic boundary condition. because the boundary condiiton is applied during the assembly of the global stiffness matrix and right force vector. If I have 2 load cases, I need to do the assembly two times. Is it possible to only do once assembly in LibMesh meanwhile considering the periodic boundary condition? Thanks for any suggestions! -- Best regards, Yours sincerely ShengliXu Department of Engineering Mechanics State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian, 116023, P. R. China Email:shengli@... shengli.xu.xu@... ========================== ```
 Re: [Libmesh-users] Multi-Load case with periodic boundary condition From: Roy Stogner - 2007-05-23 02:56:49 ```On Wed, 23 May 2007, Shengli Xu wrote: > I want to solve the multi-load case problem with periodic boundary > condition. because the boundary condiiton is applied during the assembly of > the global stiffness matrix and right force vector. If I have 2 load > cases, I need to do the assembly two times. Is it possible to only do once > assembly in LibMesh meanwhile considering the periodic boundary condition? > Thanks for any suggestions! Assuming you're currently using a LinearImplicitSystem, I would instead inherit from that class with your own subclass. Then, instead of attaching a user assembly function, override the virtual method System::assemble. Doing that allows you to avoid the matrix->zero() call in ImplicitSystem::assemble(). Instead, the first time your assemble function is called you'll assemble the matrix and all your rhs vectors, and each subsequent time assemble() is called you'll just swap the main rhs vector with whatever other load vector you want the solve() call to use. --- Roy ```