Publikace ÚTF

We provide an updated version of the program hex-ecs originally presented in Comput. Phys. Commun.
185 (2014) 2903–2912. The original version used an iterative method preconditioned by the incomplete
LU factorization (ILU), which – though very stable and predictable – requires a large amount of
working memory. In the new version we implemented a ‘‘separated electrons’’ (or ‘‘Kronecker product
approximation’’, KPA) preconditioner as suggested by Bar-On et al., Appl. Num. Math. 33 (2000) 95–104.
This preconditioner has much lower memory requirements, though in return it requires more iterations
to reach converged results. By careful choice between ILU and KPA preconditioners one is able to extend
the computational feasibility to larger calculations.
Secondly, we added the option to run the KPA preconditioner on an OpenCL device (e.g. GPU). GPUs
have generally better memory access times, which speeds up particularly the sparse matrix multiplication.