Front page › Forums › General › FGMRES faster than GMRES
Tagged: FGMRES, gmres, ILU
This topic contains 3 replies, has 2 voices, and was last updated by Mohamed 1 year, 10 months ago.
I observed for the matrices and RHS I generate in my case that FGMRES is faster than GMRES, while both use ILU and show the same number of linear iterations to convergence.
I expected FGMRES with the same preconditioner to have the same performance as GMRES since they performs the same linear iterations.
Can you please comment on that (I could provide matrix and RHS )
Yes, this is a bit unexpected. Typically, FGMRES could require less iteration to convergence than the pure GMRES.
Can you say something more about your linear system? How big is the problem?
What kind of timing do you get?
Correction, actually this FMGRES implementation uses one application of the preconditioner less. Thus, it should perform slightly better than the pure GMRES. You can check the files directly (gmres.cpp and fgmres.cpp)
You must be logged in to reply to this topic.
PARALUTION 1.1.0 - 25th of Jan 2016