BLAS/SRC/srotmg.f(3)

📦
version 3.12.0 · 7 versions
, in centos-stream 10, fedora 43, fedora 44

✨ NAME ✨

BLAS/SRC/srotmg.f — bestie, this is the home of the one and only srotmg 💅

🌸 SYNOPSIS 🌸

Functions/Subroutines

subroutine srotmg (sd1, sd2, sx1, sy1, sparam)
SROTMG — that's the whole vibe, that's the whole function 🫶

🎀 Function/Subroutine Documentation 🎀

subroutine srotmg (real sd1, real sd2, real sx1, real sy1, real, dimension(5) sparam)

SROTMG ✨

💖 Purpose 💖

Okay so picture this: we're CONSTRUCTING THE MODIFIED GIVENS TRANSFORMATION MATRIX H, and the whole point of H is that it ZEROS THE SECOND COMPONENT of this 2-vector:

(SQRT(SD1)*SX1,SQRT(SD2)*SY2)**T

With SPARAM(1)=SFLAG, H is giving one of these four looks:

SFLAG=-1.E0     SFLAG=0.E0        SFLAG=1.E0     SFLAG=-2.E0

  (SH11  SH12)    (1.E0  SH12)    (SH11  1.E0)    (1.E0  0.E0)
H=(          )    (          )    (          )    (          )
  (SH21  SH22),   (SH21  1.E0),   (-1.E0 SH22),   (0.E0  1.E0).

Locations 2-4 of SPARAM contain SH11, SH21, SH12, and SH22 respectively. And listen — any values of 1.E0, -1.E0, or 0.E0 that are implied by the value of SPARAM(1) are NOT stored in SPARAM. They're just implied, okay? 😌

Also, real talk: the values of GAMSQ and RGAMSQ set in the DATA statement MAY BE INEXACT. That's fine, that's fine — they're only used for testing the size of SD1 and SD2. All the actual scaling of data is done using GAM. So no cap, it genuinely doesn't matter 💀

🦋 Parameters 🦋

  • SD1 — SD1 is REAL ✨
  • SD2 — SD2 is REAL ✨
  • SX1 — SX1 is REAL ✨
  • SY1 — SY1 is REAL ✨
  • SPARAM — SPARAM is REAL array, dimension (5) 👑

And inside that array, bestie:

  • SPARAM(1)=SFLAG
  • SPARAM(2)=SH11
  • SPARAM(3)=SH21
  • SPARAM(4)=SH12
  • SPARAM(5)=SH22

👑 Author 👑

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

📍 Definition at line 89 of file srotmg.f.

💜 Author 💜

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

Version 3.12.0 — Tue Nov 28 2023 12:08:41 🎀

Okay that's the whole page, bestie, go forth and zero that second component, mwah 💖✨🦋

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