[bddcml-users] Complex number support

[Jakub Sistek]

Hi Sebastian,

first of all, thank you for your interest in BDDCML!

So far, there has been no need for supporting complex numbers in BDDCML, 
so you are the first one asking for this :-) What applications do you 
have in mind?

Implementation-wise, this may not be too bad, as you suggest, although 
the "double" type is hard-coded in a lot of subroutines where it would 
require changing. Even blopex has a version for complex numbers, 
although one should start without the adaptivity. And yes, it would be 
applicable only to Hermitian matrices. MUMPS supports all the types one 
needs, so this should be straightforward.

More flexible variable types would be helpful in other scenarios I am 
interested in, such as
* using long integers for certain indices for very large problems
* using single precision instead of double

Also algorithmically, I am not aware of any principal issues. I know 
other DD codes support complex numbers, such as HPDDM or the PCBDDC 
preconditioner in PETSc. I know the developers, so I would be able to 
ask for advice.

This would actually be a nice extension of the functionality of BDDCML! 
If you were interested in helping with this, I would be happy to give 
you access to the project on Github and we could try to devise such 
version in a new branch together.

Let me know what you think.

Best wishes,

Jakub



On 22/01/2021 05:29, Sebastian Grimberg wrote:
> Hello everyone,
>
> I’m a new user and am wondering if there is any interest or thoughts 
> on supporting complex numbers in BDDCML? I’m unsure about the blopex 
> dependency for adaptivity, and further it may not even be applicable 
> unless the input materials is Hermitian, but it seems like it could be 
> doable by calling the correct MUMPS library and adjusting the 
> interface a bit. Would this be worth spending time to develop, and are 
> there any other foreseeable issues?
>
> Cheers,
>
> Sebastian Grimberg
>
> _______________________________________________
> bddcml-users mailing list
> bddcml-users at math.cas.cz
> https://list.math.cas.cz/listinfo/bddcml-users


-- 
Jakub Sistek, Ph.D.

Researcher
Institute of Mathematics
Czech Academy of Sciences

sistek at math.cas.cz
http://www.math.cas.cz/~sistek
+420 222 090 710

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