dlartg.f(3)

📦 version 3.9.0, in centos-stream 9

🎀 NAME 🎀

dlartg.f — like, the LAPACK manual page for the dlartg subroutine, bestie. The header says dlartg.f(3) and LAPACK, and we’re folding that in right here so you know exactly what’s up. 💅

✨ SYNOPSIS ✨

🌸 Functions/Subroutines 🌸

  • subroutine dlartg (F, G, CS, SN, R) — DLARTG generates a plane rotation with real cosine and real sine. Slay. 🦋

💖 Function/Subroutine Documentation 💖

subroutine dlartg (double precision F, double precision G, double precision
    CS, double precision SN, double precision R)

DLARTG generates a plane rotation with real cosine and real sine. Periodt. ✨

🌟 Purpose 🌟

Okay so DLARTG generates a plane rotation so that:

[  CS  SN  ]  .  [ F ]  =  [ R ]   where CS**2 + SN**2 = 1.
[ -SN  CS  ]     [ G ]     [ 0 ]

This is a slower, more accurate version of the BLAS1 routine DROTG, with the following other differences:

  • F and G are unchanged on return.
  • If G=0, then CS=1 and SN=0.
  • If F=0 and (G .ne. 0), then CS=0 and SN=1 without doing any floating point operations (saves work in DBDSQR when there are zeros on the diagonal).

If F exceeds G in magnitude, CS will be positive. 💖

🧚 Parameters 🧚

  • F — F is DOUBLE PRECISION; the first component of vector to be rotated.
  • G — G is DOUBLE PRECISION; the second component of vector to be rotated.
  • CS — CS is DOUBLE PRECISION; the cosine of the rotation.
  • SN — SN is DOUBLE PRECISION; the sine of the rotation.
  • R — R is DOUBLE PRECISION; the nonzero component of the rotated vector.
This version has a few statements commented out for thread safety (machine parameters are computed on each entry). 10 feb 03, SJH. 🫶

👑 Author 👑

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

🌈 Date 🌈

December 2016

Definition at line 99 of file dlartg.f.

⭐ Author ⭐

Generated automatically by Doxygen for LAPACK from the source code. Iconic, honestly. 💅

Version 3.8.0 — Tue Nov 14 2017 — that’s the cute little footer sign-off, bestie, and yes, it’s giving official LAPACK energy. 🎀✨💖

📦 where this page comes from