Commit 14f16b59 authored by Andreas Marek's avatar Andreas Marek
Browse files

Update documentation about checking the blacs distribution

parent 532b09f8
......@@ -376,6 +376,8 @@ to be done in the application using MPI which wants to call ELPA, namely
- Initializing the MPI
- creating a blacs distributed matrix
- IMPORTANT: it is very, very important that you check the return value of "descinit" of your blacs distribution!
ELPA relies that the distribution it should work on is _valid_. If this is not the case the behavior is undefined!
- using this matrix within ELPA
The skeleton is not ment to be copied and pasted, since the details will always be dependent on the application which should
......@@ -438,6 +440,12 @@ call BLACS_Gridinfo( my_blacs_ctxt, nprow, npcol, my_prow, my_pcol )
call descinit( sc_desc, na, na, nblk, nblk, 0, 0, my_blacs_ctxt, na_rows, info )
! check the return code
if (info .ne. 0) then
print *,"Invalid blacs-distribution. Abort!"
stop
endif
! Allocate matrices
allocate(a (na_rows,na_cols))
......
......@@ -100,6 +100,13 @@
!> \brief Abstract definition of the elpa_t type
!>
!>
!> Since ELPA needs (in case of MPI builds) that the matix is block-cyclic distributed
!> the user has to ensure this distribution _before_ calling ELPA.
!> Experience shows, that it is very important that the user checks the return code of
!> 'descinit' to check whether the block-cyclic distribution is valid.
!> Note that ELPA relies on a valid block-cyclic distribution and might show unexpected
!> behavior if this has not been ensured before calling ELPA.
!>
!> A typical usage of ELPA might look like this:
!>
!> Fortran synopsis
......
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