lis_esolve...sidualnorms(3)

📦 version 2.1.11, in fedora 43, fedora 44, nixos 26.05, nixpkgs unstable

💖 lis_esolver_get_residualnorms — bestie edition 💖

okay so this is a page from the Lis Library Functions manual (that's the lis(3) manual, yes, and yes she's iconic) and we're about to learn how to get your residual norms back out of the eigensolver. sit down, hydrate, let's go 🫶

✨ NAME ✨

lis_esolver_get_residualnorms — get the relative residual norm for all the eigenpairs from the eigensolver

like. ALL of them. not one. all. we love a completionist queen 👑

✨ SYNOPSIS ✨

#include "lis.h"

LIS_INT lis_esolver_get_residualnorms(LIS_ESOLVER esolver, LIS_VECTOR
v);

no cap, that's the whole signature, copy it exactly, don't be cute with it 🙈

✨ DESCRIPTION ✨

okay so here's the tea: this function gets the relative residual norms for every single eigenpair your eigensolver produced. the formula, bestie, is literally this:

||lx - Ax||_2/||lx||_2

that's it. that's the math. ||lx - Ax||_2/||lx||_2, exactly like that, no edits. it's giving "how far off are we from an actual eigenpair, relative to the size of lx" 💅

✨ INPUT ✨

  • esolver — the eigensolver. your main character. the one doing the actual work here 🌟

✨ OUTPUT ✨

  • v — the vector that stores the residual norms 🎀 she's holding all of them for you, so be nice to her.

✨ EXIT STATUS ✨

the following exit values are returned, and we do check them, periodt:

  • 0 — the process is normally terminated ✅ slay, everything's fine, we love that for us
  • unspecified — an error occurred 💀 that's it, that's the whole description, no further info, and honestly? relatable.
fr fr, unspecified is not a vibe, it's a warning. check your stuff.

✨ SEE ALSO ✨

go, read, explore, that link is your bestie now 🦋

okay so that's the whole page!! tysm for reading, you ate that 💅

sign-off time: this was the Lis Library Functions manual page, and the footer says it's from 28 Aug 2014 — a vintage queen, honestly, and she still serves 👑✨🌸

Man Page · 28 Aug 2014 · lis_esolve...sidualnorms(3) 💖

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