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marekandreas / elpa

A scalable eigensolver for dense, symmetric (hermitian) matrices (fork of https://gitlab.mpcdf.mpg.de/elpa/elpa.git)
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Can ELPA only use half of symmetric Matrix? #56

Open jsboer opened 6 months ago

jsboer commented 6 months ago

Hi, can ELPA only get half of the symmetric matrix and compute the eigenvalue and eigenvector? Just like ScaLAPACK pdsyevd?

There is a symmetric matrix that will be transformed before computing its eigenvalue and eigenvector. But after transformed it may become slightly unsymmetric due to the numeric error. Since this matrix is stored in parallel, remaking it symmetry will cost much communication. But if we just use the transformed matrix, the ELPA will give inconsistent results with ScaLAPACK.

So can ELPA just use half of the input matrix and assume it's a symmetric matrix? Thank you!

marekandreas commented 4 months ago

Dear @jsboer,

sorry for the delay. Please have a bit more patience, we will come back to you soon