|
[Sponsors] |
August 5, 2012, 15:21 |
Question on ILU(0) Preconditioned GMRES
|
#1 |
Member
Shenren Xu
Join Date: Jan 2011
Location: London, U.K.
Posts: 67
Rep Power: 15 |
Dear colleagues,
I have a few questions concerning using ILU(0) for preconditioning the GMRES solver. As far as I know, ILU(0) decomposes my original system matrix A into A=L*U+R where L and R are lower and upper triangular matrices with the same non-zero pattern as my sparse matrix A. The original linear system A *x = b is then preconditioned as A_new * x = b_new where A_new=inv(U)*inv(L)*A and b_new = inv(U)*inv(L)*b. The new linear system is solved using GMRES. My questions are 1) Do I need to explicitly invert L and U? If yes, how do I invert these sparse matrix? Wouldn't the non-zero pattern be destroyed then? 2) In matlab gmres code, one calls it with gmres(... A,..., L,U,...), i.e., only L and U are needed. Then how does matlab invert them, if ever? 3) Anyone has experience on using LASPACK's ILU preconditioned GMRES? Looks like it's ILU is only implemented for symmetric matrix. Regards, Shenren |
|
August 6, 2012, 20:19 |
|
#3 |
Member
Shenren Xu
Join Date: Jan 2011
Location: London, U.K.
Posts: 67
Rep Power: 15 |
||
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Question Re Engineering Data Source | imnull | ANSYS | 0 | March 5, 2012 14:51 |
internal field question - PitzDaily Case | atareen64 | OpenFOAM Running, Solving & CFD | 2 | January 26, 2011 16:26 |
ILU(0) | Praveen. C | Main CFD Forum | 3 | April 16, 2007 07:33 |
Preconditioned Gmres | carlos | Main CFD Forum | 2 | April 14, 2003 06:24 |
Nonlinear/Linear GMRES is... | Saebyuk | Main CFD Forum | 0 | May 10, 1999 09:31 |