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elpa_eigenvectors_float(3) Library Functions Manual elpa_eigenvectors_float(3)

NAME
       elpa_eigenvectors_float - computes the eigenvalues and (part of)	the
       eigenvector spectrum for	a real symmetric matrix

SYNOPSIS
   FORTRAN INTERFACE
       use elpa
       class(elpa_t), pointer :: elpa

       call elpa%eigenvectors_float (a,	ev, q, error)

       With the	definitions of the input and output variables:

       class(elpa_t) ::	elpa  !	returns	an instance of the ELPA	object

       datatype	:: a
	      The  matrix  a for which the eigenvalues should be computed. The
	      dimensions of matrix a must  be  set  BEFORE  with  the  methods
	      elpa_set(3)  and	elpa_setup(3). The datatype of the matrix must
	      be "real(kind=c_float)". The matrix has to be symmetric, this is
	      not checked by the routine. In case of a GPU build a  can	 be  a
	      device pointer to	a matrix a on the device memory.

       datatype	:: ev
	      The  vector ev where the eigenvalues will	be stored in ascending
	      order.   The   datatype	of   the    vector    ev    must    be
	      "real(kind=c_float)".  In	case of	a GPU build ev can be a	device
	      pointer to the vectors of	eigenvalues in the device memory.

       datatype	:: q
	      The storage space	for the	computed eigenvectors. The  dimensions
	      of  matrix a must	be set BEFORE with the methods elpa_set(3) and
	      elpa_setup(3).   The   datatype	of   the   matrix   must    be
	      "real(kind=c_float)".  In	 case of a GPU build q can be a	device
	      pointer to a matrix q on the device memory.

       integer,	optional :: error
	      The return error code of the function. Should be "ELPA_OK".  The
	      error code can be	querried with the function elpa_strerr(3)

   C INTERFACE
       #include	<elpa/elpa.h>
       elpa_t handle;

       void  elpa_eigenvectors_float(elpa_t handle, datatype *a, datatype *ev,
       datatype	*q, int	*error);

       With the	definitions of the input and output variables:

       elpa_t handle;
	      The handle to the	ELPA object

       datatype	*a;
	      The matrix a for which the eigenvalues should be	computed.  The
	      dimensions  of  the  matrix  must	be set BEFORE with the methods
	      elpa_set(3) and elpa_setup(3). The datatype must be "float". The
	      matrix has to be symmetric, this is not checked by the  routine.
	      In  case	of a GPU build a can be	a device pointer to a matrix a
	      on the device memory.

       datatype	*ev;
	      The storage for the computed eigenvalues.	 Eigenvalues  will  be
	      stored  in ascendig order. The datatype must be "float". In case
	      of a GPU build ev	can be a device	 pointer  to  the  vectors  of
	      eigenvalues in the device	memory.

       datatype	*q;
	      The  storage space for the computed eigenvectors.	The dimensions
	      of the matrix must be set	BEFORE with  the  methods  elpa_set(3)
	      and  elpa_setup(3). The datatype must be one of "float". In case
	      of a GPU build q can be a	device pointer to a matrix  q  on  the
	      device memory.

       int *error;
	      The  error  code of the function.	Should be "ELPA_OK". The error
	      codes can	be querried with elpa_strerr(3)

DESCRIPTION
       Compute the eigenvalues and (parts of) the eigenvector  spectrum	 of  a
       real  symmetric	single	precision  matrix.The  functions elpa_init(3),
       elpa_allocate(3), elpa_set(3), and elpa_setup(3)	must be	called	BEFORE
       elpa_eigenvalues	 can  be called. Especially the	number of eigenvectors
       to be computed can be set with elpa_set(3)

SEE ALSO
       elpa2_print_kernels(1)	elpa_init(3)   elpa_allocate(3)	   elpa_set(3)
       elpa_setup(3)		 elpa_strerr(3)		   elpa_eigenvalues(3)
       elpa_skew_eigenvalues(3)	  elpa_skew_eigenvectors(3)   elpa_cholesky(3)
       elpa_invert_triangular(3)		     elpa_solve_tridiagonal(3)
       elpa_hermitian_multiply(3) elpa_uninit(3) elpa_deallocate(3)

ELPA			       Wed Sept	01 2021	    elpa_eigenvectors_float(3)

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