elpa_eigenvectors(3)

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

6       elpa_eigenvectors - computes the eigenvalues and (part of) the
7       eigenvector spectrum for a real symmetric or complex hermitian matrix
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SYNOPSIS

11   FORTRAN INTERFACE
12       use elpa
13       class(elpa_t), pointer :: elpa
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15       call elpa%eigenvectors (a, ev, q, error)
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17       With the definitions of the input and output variables:
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19       class(elpa_t) :: elpa  ! returns an instance of the ELPA object
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21       datatype :: a
22              The matrix a for which the eigenvalues should be computed. The
23              dimensions of matrix a must be set BEFORE with the methods
24              elpa_set(3) and elpa_setup(3). The datatype of the matrix can be
25              one of "real(kind=c_double)", "real(kind=c_float)",
26              "complex(kind=c_double)", or "complex(kind=c_float)". The matrix
27              has to be symmetric or hermitian, this is not checked by the
28              routine.
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30       datatype :: ev
31              The vector ev where the eigenvalues will be stored in ascending
32              order. The datatype of the vector ev can be either
33              "real(kind=c_double)", or "real(kind=c_float)", depending of the
34              datatype of the matrix. Note that complex hermitian matrices
35              also have real valued eigenvalues.  datatype :: q The storage
36              space for the computed eigenvectors. The dimensions of matrix a
37              must be set BEFORE with the methods elpa_set(3) and
38              elpa_setup(3). The datatype of the matrix can be one of
39              "real(kind=c_double)", "real(kind=c_float)",
40              "complex(kind=c_double)", or "complex(kind=c_float)"
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42       integer, optional :: error
43              The return error code of the function. Should be "ELPA_OK". The
44              error code can be querried with the function elpa_strerr(3)
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47   C INTERFACE
48       #include <elpa/elpa.h>
49       elpa_t handle;
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51       void elpa_eigenvalues(elpa_t handle, datatype *a, datatype *ev,
52       datatype *q, int *error);
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54       With the definitions of the input and output variables:
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57       elpa_t handle;
58              The handle to the ELPA object
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60       datatype *a;
61              The matrix a for which the eigenvalues should be computed. The
62              dimensions of the matrix must be set BEFORE with the methods
63              elpa_set(3) and elpa_setup(3). The datatype can be one of
64              "double", "float", "double complex", or "float complex". The
65              matrix has to be symmetric or hermitian, this is not checked by
66              the routine.
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68       datatype *ev;
69              The storage for the computed eigenvalues. Eigenvalues will be
70              stored in ascendig order. The datatype can be either "double" or
71              "float". Note that the eigenvalues of complex hermitian matrices
72              are also real.
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74       datatype *q;
75              The storage space for the computed eigenvectors. The dimensions
76              of the matrix must be set BEFORE with the methods elpa_set(3)
77              and elpa_setup(3). The datatype can be one of "double", "float",
78              "double complex", or "float complex".
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80       int *error;
81              The error code of the function. Should be "ELPA_OK". The error
82              codes can be querried with elpa_strerr(3)
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DESCRIPTION

86       Compute the eigenvalues and (parts of) the eigenvector spectrum of a
87       real symmetric or complex hermitian matrix.The functions elpa_init(3),
88       elpa_allocate(3), elpa_set(3), and elpa_setup(3) must be called BEFORE
89       elpa_eigenvalues can be called. Especially the number of eigenvectors
90       to be computed can be set with elpa_set(3)
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NAME

SYNOPSIS

DESCRIPTION

SEE ALSO