elpa_eigenvalues(3)

🌸 NAME 🌸

okay so, welcome to elpa_eigenvalues(3) from the Library Functions Manual — this page is literally about computing all eigenvalues λ for a real symmetric or complex hermitian eigenproblem: A*Q = λ*Q. iconic behavior 💅

There are also variations of this routine that can accept not only host but also device pointers as input/output. Names of these routines explicitly contain the corresponding datatypes: elpa_eigenvalues_double, elpa_eigenvalues_float, elpa_eigenvalues_double_complex, elpa_eigenvalues_float_complex. iykyk ✨

✨ SYNOPSIS ✨

🧚 FORTRAN INTERFACE 🧚

use elpa
class(elpa_t), pointer :: elpa_handle

call elpa_handle%eigenvalues (a, ev, error)

With the definitions of the input and output variables, bestie:

• class(elpa_t) :: elpa_handle — an instance of the ELPA object. main character handle energy 🎀
• datatype :: a — the local part of 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 can be one of "real(kind=c_double)", "real(kind=c_float)", "complex(kind=c_double)", or "complex(kind=c_float)". The global matrix has to be symmetric or hermitian, this is not checked by the routine. 🚨
• datatype_real :: ev — the global 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. Note that complex hermitian matrices also have real eigenvalues. slay 💖
• 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 *a, datatype_real *ev, int *error);

With the definitions of the input and output variables:

• elpa_t elpa_handle; — the handle to the ELPA object. your ELPA passport 🦋
• datatype *a; — the local part of 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 can be one of "double", "float", "double complex"/"std::complex<double>", "float complex"/"std::complex<float>" for C/C++. The global matrix has to be symmetric or hermitian, this is not checked by the routine. 💀
• datatype_real *ev; — the global array where the eigenvalues λ will be stored in ascending order. The datatype_real of the vector ev can be either "double" or "float", depending of the datatype of the matrix. Note that complex hermitian matrices also have real eigenvalues. real eigenvalues only, no cap ⭐
• 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 of a real symmetric or complex hermitian matrix. the way that this is the whole vibe 💅

The functions elpa_init(3), elpa_allocate(3), elpa_set(3), and elpa_setup(3) must be called BEFORE elpa_eigenvalues can be called. order matters, bestie ✅

💅 SEE ALSO 💅

you also gotta check out these icons:

• elpa2_print_kernels(1)
• elpa_init(3)
• elpa_allocate(3)
• elpa_set(3)
• elpa_setup(3)
• elpa_strerr(3)
• elpa_skew_eigenvalues(3)
• elpa_eigenvectors(3)
• elpa_skew_eigenvectors(3)
• elpa_cholesky(3)
• elpa_invert_triangular(3)
• elpa_solve_tridiagonal(3)
• elpa_eigenvalues(3)
• elpa_uninit(3)
• elpa_deallocate(3)

mwah 💋 — source/version: ELPA; date: Thu Nov 28 2024; page: elpa_eigenvalues(3). periodt. 🌈👑