zlartg.f(3)

🌸 NAME 🌸

okay so this is the zlartg.f page from the LAPACK manual, and bestie, it’s giving “tiny subroutine, big rotation energy” 💫. We’re talking about zlartg — the icon that generates a plane rotation with real cosine and complex sine. Periodt.

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✨ SYNOPSIS ✨

🧚 Functions/Subroutines

• subroutine zlartg (F, G, CS, SN, R) — ZLARTG generates a plane rotation with real cosine and complex sine.

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📚 Function/Subroutine Documentation 📚

🌀 subroutine zlartg (complex*16 F, complex*16 G, double precision CS, complex*16 SN, complex*16 R)

ZLARTG generates a plane rotation with real cosine and complex sine. lowkey iconic.

🎯 Purpose

Okay so ZLARTG generates a plane rotation so that:

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

This is a faster version of the BLAS1 routine ZROTG, except for the following differences:

• F and G are unchanged on return.
• If G=0, then CS=1 and SN=0.
• If F=0, then CS=0 and SN is chosen so that R is real.

bestie the vibe check here is: it’s like ZROTG but faster, and with those exact differences. don’t forget them 🫶

🧾 Parameters

• F — F is COMPLEX*16. The first component of vector to be rotated.
• G — G is COMPLEX*16. The second component of vector to be rotated.
• CS — CS is DOUBLE PRECISION. The cosine of the rotation.
• SN — SN is COMPLEX*16. The sine of the rotation.
• R — R is COMPLEX*16. The nonzero component of the rotated vector.

👑 Author

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

📅 Date

December 2016

🔍 Further Details

• 3-5-96 - Modified with a new algorithm by W. Kahan and J. Demmel
• This version has a few statements commented out for thread safety (machine parameters are computed on each entry). 10 feb 03, SJH.

Definition at line 105 of file zlartg.f.

👑 Author

Generated automatically by Doxygen for LAPACK from the source code.

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✨ cute little sign-off time ✨

This was Version 3.8.0, dated Tue Nov 14 2017 — and yeah, it was generated automatically by Doxygen for LAPACK from the source code. slay, documentation pipeline, slay 💅🎀