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[Scalapack] Scalapack Vector Issues

Hi,

My name is Jason Sadowski and am currently performing research in the 
Department of Physics and Engineering Physics at the University of 
Saskatchewan.  I am using ScaLapack to perform calculations for the 
project I am currently working on which is a study of the interface 
between d-wave and s-wave superconductivity.  I have a few questions 
regarding efficient access of the distributed matrix elements.  First I 
will quickly summarize the calculation I am trying to perform.

For this project I must essentially solve an eigenvalue problem 
repeatedly.  For this I am using the routine PDSYEVD to generate the 
eigenvalues and eigenvectors on a distributed memory architecture.  The 
diagonalization of the matrix with this routine is very fast,  however 
the problem I have comes from the analysis after the diagonalization.  
The overall routine is an iterative process, so I must perform some 
calculation using the eigenvectors, and then use the results to 
re-evaluate the matrix elements and repeat this until the results 
converge. 

The problem is that accessing the eigenvectors using PDELGET requires 
upwards of 10x more time than the original diagonalization routine (Due 
to the repeated broadcasts).  This extra time eliminates the advantage 
of using a parallel routine.  Is it possible to broadcast the 
distributed matrix of eigenvectors so that all nodes have a copy of the 
total matrix (similar to the allgatther operation in mpi) ?

Thanks in advance,

Jason Sadowski

Department of Physics and Engineering Physics
University of Saskatchewan


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