Eigenvalue SoLvers for Petaflop-Applications (ELPA)  2017.05.001.rc1
Eigenvalue SoLvers for Petaflop-Applications (ELPA) Documentation

Eigenvalue SoLvers for Petaflop-Applications (ELPA)

http://elpa.mpcdf.mpg.de
The ELPA library was originally created by the ELPA consortium, consisting of the following organizations:

Some parts and enhancements of ELPA have been contributed and authored by the Intel Corporation and Nvidia Corporation, which are not part of the ELPA consortium.

Maintainance and development of the ELPA library is done by the Max Planck Computing and Data Facility (MPCDF)

Futher support of the ELPA library is done by the ELPA-AEO consortium, consisting of the following organizations:

Contributions to the ELPA source have been authored by (in alphabetical order):

Author
T. Auckenthaler, Volker Blum, A. Heinecke, L. Huedepohl, R. Johanni, Werner Jürgens, Pavel Kus, and A. Marek

All the important information is in the elpa_api::elpa_t derived type

Abstract definition of the elpa_t type

A typical usage of ELPA might look like this:

Fortran synopsis

use elpa
class(elpa_t), pointer :: elpa
if (elpa_init(20170403) /= elpa_ok) then
print *, "ELPA API version not supported"
stop
endif
! set parameters decribing the matrix and it's MPI distribution
call elpa%set("na", na, success)
call elpa%set("nev", nev, success)
call elpa%set("local_nrows", na_rows, success)
call elpa%set("local_ncols", na_cols, success)
call elpa%set("nblk", nblk, success)
call elpa%set("mpi_comm_parent", mpi_comm_world, success)
call elpa%set("process_row", my_prow, success)
call elpa%set("process_col", my_pcol, success)
succes = elpa%setup()
! if desired, set tunable run-time options
call e%set("solver", elpa_solver_2stage, success)

... set and get all other options that are desired

! use method solve to solve the eigenvalue problem to obtain eigenvalues
! and eigenvectors
! other possible methods are desribed in \ref elpa_api::elpa_t derived type
call e%eigenvectors(a, ev, z, success)
! cleanup

C synopsis

#include <elpa/elpa.h>
elpa_t handle;
if (elpa_init(20170403) != ELPA_OK) {
fprintf(stderr, "Error: ELPA API version not supported");
exit(1);
}
handle = elpa_allocate(&error);
/* Set parameters the matrix and it's MPI distribution */
elpa_set(handle, "na", na, &error);
elpa_set(handle, "nev", nev, &error);
elpa_set(handle, "local_nrows", na_rows, &error);
elpa_set(handle, "local_ncols", na_cols, &error);
elpa_set(handle, "nblk", nblk, &error);
elpa_set(handle, "mpi_comm_parent", MPI_Comm_c2f(MPI_COMM_WORLD), &error);
elpa_set(handle, "process_row", my_prow, &error);
elpa_set(handle, "process_col", my_pcol, &error);
/* Setup */
elpa_setup(handle);
/* if desired, set tunable run-time options */
elpa_set(handle, "solver", ELPA_SOLVER_2STAGE, &error);

... set and get all other options that are desired

/* use method solve to solve the eigenvalue problem */
/* other possible methods are desribed in \ref elpa_api::elpa_t derived type */
elpa_eigenvectors(handle, a, ev, z, &error);
/* cleanup */

Fortran module to use the ELPA library. No other module shoule be used