I've attached the message from Ben Kirk. Also attached is the example program that he sent out. See below for his original mail.
On a side note, I have written a working code with Matrix-free technique to solve a nonlinear, transient diffusion-reaction problem. It still needs few refinements and I will send it here or maybe upload it somewhere soon for all those interested. -----Original Message----- From: Benjamin Kirk [mailto:[EMAIL PROTECTED] Sent: Wednesday, January 23, 2008 9:40 AM To: Vijay M; [EMAIL PROTECTED] Subject: Re: [Libmesh-users] Support for Matrix-free algorithms Here is a really, really raw example, the comments are not clear right now, but I wanted to keep you informed. This requires the latest svn branch to work. Unpack it in the ./examples directory and run make. Run it as $ ./ex19-dbg -snes_view -r 4 for a successive approximation which will converge linearly, and $ ./ex19-dbg -snes_view -r 4 -snes_mf_operator for a matrix-free approach in the iterative solver which will converge quadratically. > Anyway, I do have a question regarding using PETSc object with LibMesh. I > have been trying to use Petsc objects Mats, Vecs and SNES solver with > Libmesh but the one thing I cant seem figure out is how to set the > nonlinear_solver public attribute of say a NonlinearImplicitSystem object to > a PETSc SNES object which I have created and initialized separately. Since, > the SNES object used in the wrapper PetscNonlinearSolver is private, I don¹t > understand how this can be done. > > Have I missed something and taken a completely wrong path on this ? I would > very much appreciate any comments that you can provide to help me out here. The user interface is totally up for discussion since I am the only one who as exercised it to date. (I am sure Roy will have some comments!) It seems to me the right approach will be to add a method which gives the user access to the SNES object? From there the KSP, Mat, Vec, PC, etc... can be accessed. This would be similar to the approach used in the PetscLinearSolver. -Ben -----Original Message----- From: li pan [mailto:[EMAIL PROTECTED] Sent: Wednesday, January 30, 2008 3:25 AM To: [email protected] Cc: [EMAIL PROTECTED] Subject: matrix free scheme Dear all, I remember that there was a discussion about matrix free scheme with libmesh before X'mas. I'd like to ask if somebody has got a example code for this. thanx pan ____________________________________________________________________________ ________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.16/1251 - Release Date: 1/30/2008 9:29 AM No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.16/1251 - Release Date: 1/30/2008 9:29 AM
ex19.tar.gz
Description: GNU Zip compressed data
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