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)"
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28       datatype :: ev
29              The vector ev where the eigenvalues will be stored in ascending
30              order. The datatype of the vector ev can be either
31              "real(kind=c_double)", or "real(kind=c_float)", depending of the
32              datatype of the matrix. Note that complex hermitian matrices
33              also have real valued eigenvalues.  datatype :: q The storage
34              space for the computed eigenvectors. The dimensions of matrix a
35              must be set BEFORE with the methods elpa_set(3) and
36              elpa_setup(3). The datatype of the matrix can be one of
37              "real(kind=c_double)", "real(kind=c_float)",
38              "complex(kind=c_double)", or "complex(kind=c_float)"
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40       integer, optional :: error
41              The return error code of the function. Should be "ELPA_OK". The
42              error code can be querried with the function elpa_strerr(3)
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45   C INTERFACE
46       #include <elpa/elpa.h>
47       elpa_t handle;
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49       void elpa_eigenvalues(elpa_t handle, datatype *a, datatype *ev,
50       datatype *q, int *error);
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52       With the definitions of the input and output variables:
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55       elpa_t handle;
56              The handle to the ELPA object
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58       datatype *a;
59              The matrix a for which the eigenvalues should be computed. The
60              dimensions of the matrix must be set BEFORE with the methods
61              elpa_set(3) and elpa_setup(3). The datatype can be one of
62              "double", "float", "double complex", or "float complex".
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64       datatype *ev;
65              The storage for the computed eigenvalues. Eigenvalues will be
66              stored in ascendig order. The datatype can be either "double" or
67              "float". Note that the eigenvalues of complex hermitian matrices
68              are also real.
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70       datatype *q;
71              The storage space for the computed eigenvectors. The dimensions
72              of the matrix must be set BEFORE with the methods elpa_set(3)
73              and elpa_setup(3). The datatype can be one of "double", "float",
74              "double complex", or "float complex".
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76       int *error;
77              The error code of the function. Should be "ELPA_OK". The error
78              codes can be querried with elpa_strerr(3)
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DESCRIPTION

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

SYNOPSIS

DESCRIPTION

SEE ALSO