elpa_set(3)

1elpa_set(3)                Library Functions Manual                elpa_set(3)
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NAME

6       elpa_set - set parameter or tunables for the ELPA library
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SYNOPSIS

10   FORTRAN INTERFACE
11       use elpa
12       class(elpa_t), pointer :: elpa
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14       call elpa%set (character(*) name, datatype value, integer error)
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16       With the definitions of the input and output variables:
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19       character(*) :: name
20              the name of the option to be set
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22       datatype :: value
23              the value which should be assigned to the option name. The
24              datatype can be integer or real(kind=c_double).
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26       integer, optional :: error
27              the returned error code. On success it is ELPA_OK, otherwise an
28              error. The error code can be querried with elpa_strerr(3)
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31   C INTERFACE
32       #include <elpa/elpa.h>
33       elpa_t handle;
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35       void elpa_set (elpa_t handle, const char *name, datatype value, int
36       *error);
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38       With the definitions of the input and output variables:
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41       elpa_t handle;
42              the handle of an ELPA object, obtained before with
43              elpa_allocate(3)"
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45       const char *name;
46              the name of the option to be set.
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48       datatype value;
49              the value which should be assigned to the option name. Datatype
50              can be either int or double."
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DESCRIPTION

54       The elpa_set function is used to set parameters and tunables for the
55       run-time of the ELPA library. It returns an error code which can be
56       querried with elpa_strerr(3).
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58       Parameters:
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60       Parameters of an ELPA instance have to be set BEFORE the ELPA instance
61       is set up with the function elpa_setup(3).
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63       At the moment the following parameters are supported:
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65       "na":  integer parameter. The global matrix has size (na * na)
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67       "nev": integer parameter. The number of eigenvectors to be computed in
68              a call to elpa_eigenvectors(3). Must have dimension 1 <= nev <=
69              na.
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71       "local_nrows":
72              integer parameter. Number of matrix rows stored on this MPI
73              process.
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75       "local_ncols":
76              integer parameter. Number of matrix cols stored on this MPI
77              process.
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79       "process_row":
80              integer parameter. Process row number in the 2D domain
81              decomposition.
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83       "process_col":
84              integer parameter. Process col number in the 2D domain
85              decomposition.
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87       "mpi_comm_parent":
88              integer parameter. The parent MPI communicator which includes
89              all MPI process which are used in the 2D domain decomposition.
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91       "bandwidth":
92              integer parameter. Some ELPA compute steps can be accelerated if
93              the matrix is already in banded form. If set, ELPA assumes that
94              the bandwidth of the matrix is the value set.  "timings": Choose
95              whether time measurements should be done in the ELPA routines.
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98       Tunables:
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100       Tunables of an ELPA option can be set at anytime.
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102       At the moment the following parameters are supported:
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104       "solver":
105              Choose which solver should be used in the compute steps
106              elpa_eigenvalues(3) or elpa_eigenvectors(3). At the moment
107              allowed option are "ELPA_SOLVER_1STAGE" or "ELPA_SOLVER_2STAGE".
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109       "real_kernel":
110              Choose which real kernel should be used in the
111              elpa_eigenvalues(3) or elpa_eigenvectors(3) compute steps, if
112              solver is set to "ELPA_SOLVER_2STAGE". The available kernels can
113              be querried with elpa2_print_kernels(1).
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115       "complex_kernel":
116              Choose which complex kernel should be used in the
117              elpa_eigenvalues(3) or elpa_eigenvectors(3) compute steps, if
118              solver is set to "ELPA_SOLVER_2STAGE". The available kernels can
119              be querried with elpa2_print_kernels(1).
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121       "qr":  Choose whether in the real case computations in
122              elpa_eigenvalues(3) or elpa_eigenvectors(3) compute steps, if
123              solver is set to "ELPA_SOLVER_2STAGE", a QR decompostion should
124              be used.
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126       "qpu": Choose whether accelerated GPU calculations should be used. Only
127              available if ELPA has been build with GPU support.
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129       "debug":
130              Choose whether, in case of an error, more debug information
131              should be provided.
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NAME

SYNOPSIS

DESCRIPTION

SEE ALSO