DCHKEC(3)

💅 DCHKEC(3) — the eigen-condition estimator tester, bestie edition

okay so this is a page from the Library Functions Manual for LAPACK, and it's about the routine DCHKEC 🎀 It's a Fortran file, and the whole thing lives at /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/EIG/dchkec.f. Yes that's a long path, no I did not make it up, it's literally right there ✨

---

🌸 NAME

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/EIG/dchkec.f

that's it, that's the name, it's giving "my full government name" energy 😭

---

✨ SYNOPSIS

Functions/Subroutines

• subroutine DCHKEC (thresh, tsterr, nin, nout) — that's the one, that's our girl, labelled DCHKEC 💖

---

🦋 Function/Subroutine Documentation

subroutine DCHKEC (double precision thresh, logical tsterr, integer nin,
    integer nout)

DCHKEC — iconic, no notes 👑

🎀 Purpose:

!>
!> DCHKEC tests eigen- condition estimation routines
!>        DLALN2, DLASY2, DLANV2, DLAQTR, DLAEXC,
!>        DTRSYL, DTREXC, DTRSNA, DTRSEN, DTGEXC
!>
!> In all cases, the routine runs through a fixed set of numerical
!> examples, subjects them to various tests, and compares the test
!> results to a threshold THRESH. In addition, DTREXC, DTRSNA and DTRSEN
!> are tested by reading in precomputed examples from a file (on input
!> unit NIN).  Output is written to output unit NOUT.
!>

so basically: it's the vibe-check routine for eigen-condition estimation 🔥 It runs through a fixed set of numerical examples, puts them through a bunch of tests, and compares the test results to a threshold called THRESH. And there's extra lore: DTREXC, DTRSNA and DTRSEN get tested by reading in precomputed examples from a file, which it pulls from input unit NIN. Then everything it wants to say goes out to output unit NOUT. periodt 💅

---

💖 Parameters

• THRESH — THRESH is DOUBLE PRECISION. It's the threshold for the residual tests, and a computed test ratio passes the threshold if it is less than THRESH. (yes bestie, less than, keep that energy — lower is better here 🍓)
• TSTERR — TSTERR is LOGICAL. It's the flag that says whether error exits are to be tested. true = yes we're testing the error exits, false = not today 🙈
• NIN — NIN is INTEGER. The logical unit number for input. that's where the precomputed examples come from 📥
• NOUT — NOUT is INTEGER. The logical unit number for output. that's where the results get written 📤

---

🌈 Author

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

(an absolute squad, fr fr 🫶)

Definition at line 75 of file dchkec.f. — like, go look, it's right there, line 75, iykyk ⭐

---

👑 Author

Generated automatically by Doxygen for LAPACK from the source code. So yeah, a robot wrote this one, but it ate and left no crumbs 🤖✨

---

ngl if you're reading this because you actually have to call DCHKEC, good luck bestie, you got this 💜

---

and that's the whole page 🦋 sign-off time: this lovely thing is LAPACK, Version 3.12.0, and the footer stamps it with the date/path /home/abui...IG/dchkec.f(3) — mwah, bye, go test those eigen-condition estimators 💅🎀