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### Where can I find the linear solver documentation?

Posted: **Sun Oct 08, 2017 4:12 pm**

by **Klausb**

Hello,

I am looking for a documentation describes the setup of the MAGMA linear solvers BiCG, BiCGSTAB, CG, IDR ... and the parameters for their configuration in my application code. I assume I am overlooking something but I couldn't find it.

Klaus

### Re: Where can I find the linear solver documentation?

Posted: **Tue Oct 10, 2017 5:25 am**

by **hartwig anzt**

Dear Klaus,

I do admit that this is currently not very well documented. What we have is:

http://icl.cs.utk.edu/projectsfiles/mag ... dgesv.html
and then click on the specific solvers. For the description of the solver_par object, please look into sparse/include/magmasparse_types.h

If you have specific questions to a solver, I am happy to help. And I will try to improve the documentation in future.

Thanks, Hartwig

### Next steps

Posted: **Tue Oct 10, 2017 12:12 pm**

by **Klausb**

Dear Hartwig,

originally I worked with the following solvers which, in combination, were really fast to solve my physics problem but only 2D on the CPU, now I have to move to 3D with GPU support I think because the 3D case will have about 30.000.000 cells:

For symmetric matrices:

PCG + IC preconditioner

Start-up:

1 matrix-vector multiply

1 parallel reduction

Per iteration

1 matrix-vector multiply

3 parallel reductions

+ preconditioner - applied 1x

All other CG solvers I tried (from other libraries) crashed at an early stage of the simulation!

I tried GMRES + AMG preconditioner too but it's about 6x slower and some GMRES implementations are "rough" so the end results (of the physics problem simulation) are not as good.

For asymmetric matrices BiCG (because it's faster) and BiCGStab (when BiCG was not stable and crashed):

PBiCG + Simplified Diagonal-based Incomplete LU preconditioner

Start-up

2 matrix-vector multiplies

1 parallel reduction

Per iteration

2 matrix-vector multiplies

3 parallel reductions

+ preconditioner - applied 2x

PbiCGStab + Simplified Diagonal-based Incomplete LU preconditioner

Start-up

1 matrix-vector multiply

1 parallel reduction

Per iteration

2 matrix-vector multiplies

6 parallel reductions

+ preconditioner - applied 2x

Three questions:

1: Which magma solvers would you see as replacements for the ones described above? (just as a starting point for tests)

2: What could be the benefit from iterative refinement?

3: How could I estimate the hardware power needed (CPUs + GPUs) to solve my 3D problem (assume double precision)?

Thank you for your help!

Klaus

### Where can I find the linear solver documentation

Posted: **Sat Nov 25, 2017 4:11 am**

by **JacksonZWimpub**

Dear All,

What are the subroutines that Im supposed to call to solve the linear ODEs in that form MXCXKX = F where none of the variables denoted as M, C, K and F are function of the time?

Does anybody can enlighten me on that?

Regards,

Комплексное продвижение сайтов!

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### Re: Where can I find the linear solver documentation?

Posted: **Tue Nov 28, 2017 11:24 am**

by **mgates3**

Are you using the MAGMA computational algebra system,

http://magma.maths.usyd.edu.au/magma/ ?

If so, you're at the wrong site.

This forum is for the MAGMA linear algebra for GPUs library,

http://icl.utk.edu/magma/
-mark