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question about the usage of BGMRES #13672

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CSjkcyz opened this issue Dec 16, 2024 · 4 comments
Closed

question about the usage of BGMRES #13672

CSjkcyz opened this issue Dec 16, 2024 · 4 comments

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@CSjkcyz
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CSjkcyz commented Dec 16, 2024

BlockGmres did not converge!

Hello,
When I try to solve the problem with multiple right-terminal terms using BlockGmres method, after adding and setting blockSize>1 in BlockGmresKokkosExFile.cpp, why the result is not correct: ERROR: Belos did not converge! But setting blockSize=1 converges, does this mean that the algorithm has special requirements for solving matrices or certain parameters? The matrix I tested with is bcsstk12.mtx, num-rhs=4, blockSize=4.

Thanks!

@cgcgcg
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cgcgcg commented Dec 16, 2024

@trilinos/belos

@cgcgcg
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cgcgcg commented Dec 17, 2024

@hkthorn

@hkthorn
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hkthorn commented Dec 18, 2024

@CSjkcyz The maximum subspace for this example is 25, which works for blockSize=1. However, if you want to increase the block size to 4, the size of the subspace will need to increase. For example, increasing it to 120 seems to work for the solver to converge.

@CSjkcyz
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CSjkcyz commented Dec 20, 2024

Thank you, my problem is solved.

@cgcgcg cgcgcg closed this as completed Dec 20, 2024
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