English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The interface to the MUMPS solver was updated in the JOREK MHD code tosupport Block Low Rank (BLR) compression and an interface to the new PaStiXsolver version 6 has been implemented supporting BLR as well. First tests werecarried out with JOREK, which solves a large sparse matrix system iterativelyin each time step. For the preconditioning, a direct solver is applied in thecode to sub-matrices, and at this point BLR was applied with the results beingsummarized in this report. For a simple case with a linearly growing mode,results with both solvers look promising with a considerable reduction of thememory consumption by several ten percent was obtained. A direct increase inperformance was seen in particular configurations already.  The choice of the BLR accuracy parameter $\epsilon$ proves to be critical inthis simple test and also in more realistic simulations, which were carried outonly with MUMPS due to the limited time available. The more realistic testshowed an increase in run time when using BLR, which was mitigated when usinglarger values of $\epsilon$. However, the GMRes iterative solver does not reachconvergence anymore when $\epsilon$ is too large, since the preconditionerbecomes too inaccurate in that case. It is thus critical to use an $\epsilon$as large as possible, while still reaching convergence. More tests regardingthis optimum will be necessary in the future. BLR can also lead to an indirectspeed-up in particular cases, when the simulation can be run on a smallernumber of compute nodes due to the reduced memory consumption.

Testing performance with and without Block Low Rank Compression in MUMPS and the new PaStiX 6.0 for JOREK nonlinear MHD simulations