elpa_eigen...at_complex(3)

💖 elpa_eigenvalues_float_complex(3) — the Library Functions Manual girlie is here to explain it ✨

okay so bestie, listen: this is the page for elpa_eigenvalues_float_complex, and it's literally the glow-up you need when you want all the eigenvalues λ of a complex hermitian eigenproblem. the whole vibe is:

A*Q = λ*Q

that's it. that's the moment. 🎀

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✨ NAME ✨

elpa_eigenvalues_float_complex — computes all eigenvalues λ for a complex hermitian eigenproblem: A*Q = λ*Q 💅

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🦋 SYNOPSIS 🦋

💜 FORTRAN INTERFACE

use elpa
class(elpa_t), pointer :: elpa_handle

call elpa_handle%eigenvalues_float_complex (a, ev, error)

and here's the definition of the input and output variables, bestie — don't skip, iykyk:

• 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 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 global matrix has to be hermitian — and no, this is not checked by the routine, so that's on you 🫶. in case of a GPU build a can be a pointer to the device memory.
• real(kind=c_float) :: ev OR type(c_ptr) :: ev — the global array where the eigenvalues λ will be stored in ascending order. in case of a GPU build ev can be a pointer to the device memory. and note that complex hermitian matrices also have real eigenvalues — yes really, it's giving "math is iconic" 🌸.
• 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;

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

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

and with the definitions of the input and output variables:

• elpa_t elpa_handle; — the handle to the ELPA object 👑
• float complex *a; OR std::complex<float> *a; — the local part of the host/device 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 global matrix A has to be hermitian, and again this is not checked by the routine 🙈. in case of a GPU build a can be a pointer to the device memory.
• float *ev; — the global array where the eigenvalues λ 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, periodt 💅.
• int *error; — the error code of the function. should be "ELPA_OK". the error codes can be queried with elpa_strerr(3) ⭐.

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🔥 DESCRIPTION 🔥

computes the eigenvalues of a complex hermitian matrix. and listen — the functions elpa_init(3), elpa_allocate(3), elpa_set(3), and elpa_setup(3) must be called BEFORE elpa_eigenvalues_float_complex can be called. no shortcuts, babe, the order is the order 🧚

okay lowkey important: skip the setup and you're not slaying, you're just… not doing it. call them first. 💀

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👑 SEE ALSO 👑

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)

the whole friend group, fr fr — go read them too 🫶💖

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and that's the page, bestie!! this cutie was brought to you by ELPA, dated Thu Nov 28 2024 — like, the manual name and everything. mwah, go compute those eigenvalues. 💋✨🦋🌸🎀