lapacke_dstevr_work.c(3)

💫 lapacke_dstevr_work.c — the tridiagonal eigen-solver bestie you didn't know you needed 💫

okay so this is the manual page for lapacke_dstevr_work.c, a file from the LAPACK library (you know, the linear algebra icon). it's giving "I solve symmetric tridiagonal eigenvalue problems and I do it beautifully." this is the work-array version of LAPACKE_dstevr, meaning you have to pass in your own scratch space and we're all very honest about that. no cap. 🎀

---

✨ SYNOPSIS ✨

#include 'lapacke_utils.h'

🦋 Functions 🦋

lapack_int LAPACKE_dstevr_work (int matrix_layout, char jobz, char range,
    lapack_int n, double *d, double *e, double vl, double vu,
    lapack_int il, lapack_int iu, double abstol, lapack_int *m, double
    *w, double *z, lapack_int ldz, lapack_int *isuppz, double *work,
    lapack_int lwork, lapack_int *iwork, lapack_int liwork)

---

🌸 Function Documentation 🌸

💅 lapack_int LAPACKE_dstevr_work (int matrix_layout, char jobz, char range, lapack_int n, double * d, double * e, double vl, double vu, lapack_int il, lapack_int iu, double abstol, lapack_int * m, double * w, double * z, lapack_int ldz, lapack_int * isuppz, double * work, lapack_int lwork, lapack_int * iwork, lapack_int liwork)

Definition at line 36 of file lapacke_dstevr_work.c.

okay bestie, let's break down these parameters like we're doing a group project and you actually want to pass:

• matrix_layout — an int telling us whether your matrices are row-major or column-major. lowkey important, don't skip this one. 🙈
• jobz — a char that decides if we're just computing eigenvalues ('N') or also eigenvectors ('V'). choose wisely.
• range — a char that says whether you want all eigenvalues, a value range, or an index range. it's giving "pick your fighter." 🔥
• n — a lapack_int for the order of the matrix. like, how big is this thing.
• d — a double * pointing to the diagonal elements of your tridiagonal matrix. the main character energy of the matrix, honestly. 👑
• e — a double * pointing to the off-diagonal elements. the supporting cast. still important tho.
• vl — a double for the lower bound of the eigenvalue range (only used if range says so).
• vu — a double for the upper bound of the eigenvalue range (same deal).
• il — a lapack_int for the lower index of the eigenvalue range (only when range is index-based).
• iu — a lapack_int for the upper index of the eigenvalue range (same).
• abstol — a double for the absolute tolerance. it's the "how close is close enough" vibe check. ⭐
• m — a lapack_int * where we'll write back the total number of eigenvalues found. output bestie!
• w — a double * array where the eigenvalues get stored. the moment of truth. 💖
• z — a double * array for the eigenvectors (if you asked for them). this is where the magic lives.
• ldz — a lapack_int for the leading dimension of z. don't mess this up or it's gonna be a whole thing. 😭
• isuppz — a lapack_int * array that tells you which support of the eigenvectors is nonzero. useful for sparse vibes.
• work — a double * array for scratch space. you gotta bring your own. no free rides. 🫶
• lwork — a lapack_int for the length of work. if it's too small, the function will be like "nope" and return an error.
• iwork — a lapack_int * array for integer scratch space. same energy as work but with integers.
• liwork — a lapack_int for the length of iwork. yeah, you guessed it — gotta be big enough.

💀 warning bestie: if your lwork or liwork is too small, you're gonna have a bad time. this function does NOT hold your hand about it. it just returns an error and moves on. periodt.

---

💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code. so like, not a human, but honestly the vibes are immaculate anyway.

---

🌈 Sign-off 🌈

this gem is from LAPACK Version 3.8.0, dated Tue Nov 14 2017. a classic. an icon. a legend. fr fr. 🦋✨

now go solve those tridiagonal eigenproblems, bestie. you got this. 💅🍓