elpa_skew_eigenvectors(3)

💖 elpa_skew_eigenvectors(3) — ELPA manual, bestie edition 💖

okay so this is the ELPA manual page for elpa_skew_eigenvectors(3). It computes all eigenvalues λ and (part of) the eigenvectors for a real skew-symmetric eigenproblem: A*Q = λ*Q. yes bestie, skew-symmetric, we love a structured queen 💅

✨ NAME ✨

elpa_skew_eigenvectors — computes all eigenvalues λ and (part of) the eigenvectors for a real skew-symmetric eigenproblem: A*Q = λ*Q.

🌸 SYNOPSIS 🌸

🧚 FORTRAN INTERFACE 🧚

use elpa
class(elpa_t), pointer :: elpa_handle

call elpa_handle%skew_eigenvectors (a, ev, q, error)

With the definitions of the input and output variables:

• class(elpa_t) :: elpa — An instance of the ELPA object.
• datatype_real :: a — The local part of matrix A for which the eigenvalues and eigenvectors should be computed. The dimensions of matrix a must be set BEFORE with the methods elpa_set(3) and elpa_setup(3). The datatype_real of the matrix can be one of "real(kind=c_double)" or "real(kind=c_float)". The global matrix has to be skew-symmetric, this is not checked by the routine. no cap, it is literally not checked 😭
• datatype_real :: ev — The array where the eigenvalues λ will be stored in ascending order. The datatype_real of ev can be either "real(kind=c_double)" or "real(kind=c_float)", depending of the datatype of the matrix.
• datatype_real :: q — The storage space for the computed eigenvectors Q. The number of requested eigenpairs must be set BEFORE with the methods elpa_set(3) and elpa_setup(3). The number of requested eigenvectors must be set BEFORE with the methods elpa_set(3) and elpa_setup(3). The datatype_real can be one of "complex(kind=c_double)" or "complex(kind=c_float)". Note, that for a skew-symmetric matrix the eigenvectors are complex. The routine returns separately the real and imaginary parts of the complex eigenvectors. Thus, the storage space has to be of dimension q(#number_of_rows, 2*#number_of_columns).
• integer, optional :: error — The return error code of the function. Should be ELPA_OK. The error code can be queried with the function elpa_strerr(3).

🔥 C/C++ INTERFACE 🔥

#include <elpa/elpa.h>
elpa_t elpa_handle;

void elpa_eigenvalues(elpa_t elpa_handle, datatype_real *a,
datatype_real *ev, datatype_real *q, int *error);

With the definitions of the input and output variables:

• elpa_t elpa_handle; — The handle to the ELPA object.
• datatype_real *a; — The local part of matrix A for which the eigenvalues and eigenvectors should be computed. The dimensions of the matrix must be set BEFORE with the methods elpa_set(3) and elpa_setup(3). The datatype_real can be "double" or "float". The global matrix has to be symmetric or hermitian, this is not checked by the routine.
• datatype_real *ev; — The array where the eigenvalues λ will be stored in ascending order. Eigenvalues will be stored in ascending order. The datatype_real can be either "double" or "float".
• datatype_real *q; — The storage space for the computed eigenvectors Q. The number of requested eigenvectors must be set BEFORE with the methods elpa_set(3) and elpa_setup(3). The datatype_real can be "double complex" or "float complex". Note, that for a skew-symmetric matrix the eigenvectors are complex. The routine returns separately the real and imaginary parts of the complex eigenvectors. Thus, the storage space has to be of dimension q(#number_of_rows, 2*#number_of_columns).
• int *error; — The error code of the function. Should be ELPA_OK. The error codes can be queried with elpa_strerr(3).

🦋 DESCRIPTION 🦋

Computes the eigenvalues and (part of) the eigenvector spectrum of a real skew-symmetric matrix. The functions elpa_init(3), elpa_allocate(3), elpa_set(3), and elpa_setup(3) must be called BEFORE elpa_skew_eigenvectors can be called. In particular, the number of the requested eigenpairs, "nev", must be set with elpa_set(3). like, set it up first bestie, don't just vibe in there unprepared 💀

🌈 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_eigenvectors(3)
• elpa_cholesky(3)
• elpa_invert_triangular(3)
• elpa_solve_tridiagonal(3)
• elpa_hermitian_multiply(3)
• elpa_uninit(3)
• elpa_deallocate(3)

okay that’s the whole manual page, bestie 💖 source/version: ELPA, date: Thu Nov 28 2024. periodt ✨🎀