How to create multiple contexts

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How to create multiple contexts

Postby maciek » Tue Mar 27, 2012 5:13 am

Consider the following example
I have 4 block diagonal matrices for 8 processors and I would like to factorize them at the same time.
So I am trying to create 4 contexts, each one with 2 processors.
But it doesn't work
I am calling
call blacs_gridinit(CONTXT,ORDER,NPROW,NPCOL)
call blacs_gridinfo(CONTXT,nprow,npcol,myrow,mycol)
with
ORDER='C'
NPROW=1
NPCOL=2
I do not know what to setup for CONTXT
If I setup CONTXT=0 on processor 0,1
CONTXT=2 on processor 2,3
CONTXT=4 on processor 4,5
and
CONTXT=6 on processors 6,7
it crashes
If I setup all CONTXT=0 on all processors it creates only one context on processors 0,1 but returns CONTXT=-1 and nprow=npcol=myrow=mycol=-1 on other processors

Any help would be appreciated, since I really would like to use several SCALAPCK solvers at the same time for many block diagonal matrices
maciek
 
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Re: How to create multiple contexts

Postby rodney » Tue May 01, 2012 9:00 pm

You cannot do this in ScaLAPACK. You will need to do one matrix at a time using one context.
rodney
 
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Location: Colorado College

Re: How to create multiple contexts

Postby Julien Langou » Wed May 02, 2012 7:25 pm

I think back in 2006, I showed an example on how to do this.
See: viewtopic.php?f=2&t=136
Julien.
Julien Langou
 
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