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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Hi, Petsc Team,<br>
<br>
Recently I tested my 3D structured Poisson-style problem with ML and BoomerAMG preconditioner respectively. In comparison, ML is more efficient in preconditioning and RAM usage, but it requires 2 times more iterations on the same KSP solver, bringing down
the overall efficiency. And both PCs don't scale well. I wonder if there's any specific approach to optimizing ML to reduce KSP iterations by setting certain command line options.<br>
<br>
I also saw in some previous petsc mail archives mentioning the "local preconditioner". As some important PC like PCILU and PCICC are not available for parallel processing, it may be beneficial to apply them as local preconditioners. The question is how to
setup a local preconditioner?<br>
<br>
<br>
Thank you veru much.<br>
<br>
<br>
<br>
Zhisong Li<br>
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