SLAQR1(3)

💖 NAME 💖

Okay so the NAME line on this one is literally just the source path, no fancy one-word summary: /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/slaqr1.f. It's chilling in the Library Functions Manual as page /home/abui...RC/slaqr1.f(3), and that's the whole vibe. 🫶

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

• subroutine SLAQR1 (n, h, ldh, sr1, si1, sr2, si2, v) — SLAQR1 sets a scalar multiple of the first column of the product of 2-by-2 or 3-by-3 matrix H and specified shifts.

📚 Function/Subroutine Documentation 📚

🌸 subroutine SLAQR1 🌸

subroutine SLAQR1 (integer n, real, dimension( ldh, * ) h, integer ldh, real sr1, real si1, real sr2, real si2, real, dimension( * ) v)

SLAQR1 sets a scalar multiple of the first column of the product of 2-by-2 or 3-by-3 matrix H and specified shifts. ✨

💡 Purpose 💡

Given a 2-by-2 or 3-by-3 matrix H, SLAQR1 sets v to a scalar multiple of the first column of the product:

(*)  K = (H - (sr1 + i*si1)*I)*(H - (sr2 + i*si2)*I)

...scaling to avoid overflows and most underflows. It is assumed that either

1. sr1 = sr2 and si1 = -si2
2. si1 = si2 = 0

This is useful for starting double implicit shift bulges in the QR algorithm. 🌈

🌟 Parameters 🌟

• N — N is INTEGER. Order of the matrix H. N must be either 2 or 3.
• H — H is REAL array, dimension (LDH,N). The 2-by-2 or 3-by-3 matrix H in (*).
• LDH — LDH is INTEGER. The leading dimension of H as declared in the calling procedure. LDH >= N.
• SR1 — SR1 is REAL.
• SI1 — SI1 is REAL.
• SR2 — SR2 is REAL.
• SI2 — SI2 is REAL. The shifts in (*).
• V — V is REAL array, dimension (N). A scalar multiple of the first column of the matrix K in (*).

👑 Author 👑

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

🫶 Contributors 🫶

Karen Braman and Ralph Byers, Department of Mathematics, University of Kansas, USA.

📍 Definition 📍

Definition at line 120 of file slaqr1.f.

🤖 Author 🤖

Generated automatically by Doxygen for LAPACK from the source code.

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Okay that's the page, bestie — footer vibes are LAPACK Version 3.12.0 and /home/abui...RC/slaqr1.f(3). Slay. 💅✨