ELPA_EIGENVECTORS_FLOAT_COMPLEX(3)

okay so bestie, this is the elpa_eigenvectors_float_complex page from the ELPA Library Functions Manual — yes, the whole thing, and it's giving "complex hermitian eigenproblem but make it fashion" ✨💅

🌸 NAME 🌸

elpa_eigenvectors_float_complex — computes all eigenvalues and (part of) the eigenvectors for a complex hermitian eigenproblem: A*Q = λ*Q 👑

✨ SYNOPSIS ✨

🫶 FORTRAN INTERFACE

use elpa
class(elpa_t), pointer :: elpa_handle

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

With the definitions of the input and output variables:

• class(elpa_t) :: elpa_handle — An instance of the ELPA object. Your main character handle, fr fr.
• real(kind=c_float_complex) :: a OR type(c_ptr) :: a — The local part of the host/device matrix A for which all eigenvalues and (part of) eigenvectors should be computed. The dimensions of matrix a must be set BEFORE with the methods elpa_set(3) and elpa_setup(3). The global matrix has to be symmetric, this is not checked by the routine. In case of a GPU build a can be a pointer to the device memory. No cap, set those dimensions first 🚨
• real(kind=c_float) :: ev OR type(c_ptr) :: ev — The host/device vector ev where the eigenvalues will be stored in ascending order. In case of a GPU build ev can be a pointer to the device memory. Note that complex hermitian matrices also have real eigenvalues. Cute, right? 💖
• real(kind=c_float_complex) :: q OR type(c_ptr) :: q — The host/device storage space for the computed eigenvectors. The number of requested eigenvectors must be set BEFORE with the methods elpa_set(3) and elpa_setup(3). In case of a GPU build q can be a pointer to the device memory. Manifesting that storage space for you 🕯️✨
• 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). Bestie, check your error code, it's the vibe check of this whole situation 💀

🦋 C/C++ INTERFACE

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

// C:
void elpa_eigenvectors_float_complex(elpa_t elpa_handle, float complex
*a, float complex *ev, float complex *q, int *error);

// C++:
void elpa_eigenvalues_float_complex(elpa_t elpa_handle,
std::complex<float> *a, float *ev, std::complex<float> *q, int *error);

With the definitions of the input and output variables:

• elpa_t elpa_handle; — The handle to the ELPA object. Your little ELPA passport 🛂
• float complex *a; OR std::complex<float> *a; — The local part of the host/device matrix A for which the eigenpairs should be computed. The dimensions of the matrix must be set BEFORE with the methods elpa_set(3) and elpa_setup(3). The global matrix has to be symmetric, this is not checked by the routine. In case of a GPU build a can be a pointer to the device memory. Again: dimensions first, or it's not gonna slay 😭
• float *ev; — The host/device storage for the computed eigenvalues. Eigenvalues will be stored in ascending order. In case of a GPU build ev can be a pointer to the device memory. Ordered, organized, iconic 🌈
• float complex *q; OR std::complex<float> *q; — The host/device storage space for the computed eigenvectors. The number of requested eigenvectors must be set BEFORE with the methods elpa_set(3) and elpa_setup(3). In case of a GPU build q can be a pointer to the device memory. Set that number, bestie, it's not optional energy 🎀
• int *error; — The error code of the function. Should be "ELPA_OK". The error codes can be queried with elpa_strerr(3). That's your receipts, keep them 🧾

💜 DESCRIPTION 💜

Computes the eigenvalues and (part of) the eigenvectors of a complex hermitian matrix. The functions elpa_init(3), elpa_allocate(3), elpa_set(3), and elpa_setup(3) must be called BEFORE elpa_eigenvectors_float_complex can be called. In particular, the number of eigenvectors to be computed, "nev", must be set with elpa_set(3).

bestie this is a whole pre-game ritual: elpa_init(3) → elpa_allocate(3) → elpa_set(3) → elpa_setup(3), and then — only then — you can call elpa_eigenvectors_float_complex. Also set "nev" with elpa_set(3) or the whole thing is not giving what it's supposed to give 💅✨

🎀 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)

and that's the whole page, bestie 🫶 this little icon is from ELPA, dated Thu Nov 28 2024, and the page itself is elpa_eigen...oat_complex(3) — periodt 💅💖✨