SRC/dlas2.f(3)

✨ NAME ✨

Okay bestie, welcome to the SRC/dlas2.f(3) page from the Library Functions Manual 💅

SRC/dlas2.f — that's the whole NAME section up top, no cap. This is the page for the dlas2 routine, and it's giving very specific "I compute singular values" energy 🌸

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🎀 SYNOPSIS 🎀

🫶 Functions/Subroutines 🫶

• subroutine dlas2 (f, g, h, ssmin, ssmax) — DLAS2 computes singular values of a 2-by-2 triangular matrix. Slay 💖

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💜 FUNCTION/SUBROUTINE DOCUMENTATION 💜

Here's the full signature, bestie — read it exactly, because the types are literally part of the vibe:

subroutine dlas2 (double precision f, double precision g, double precision
       h, double precision ssmin, double precision ssmax)

DLAS2 computes singular values of a 2-by-2 triangular matrix. 🔥

🌟 Purpose

Okay so DLAS2 computes the singular values of this 2-by-2 matrix:

[  F   G  ]
[  0   H  ]

On return, SSMIN is the smaller singular value and SSMAX is the larger singular value. That's the whole assignment, and it ate 👑

🦋 Parameters

• F — F is DOUBLE PRECISION. The (1,1) element of the 2-by-2 matrix. Main character corner entry ✨
• G — G is DOUBLE PRECISION. The (1,2) element of the 2-by-2 matrix. The upper-right bestie 💫
• H — H is DOUBLE PRECISION. The (2,2) element of the 2-by-2 matrix. Bottom-right energy 🌈
• SSMIN — SSMIN is DOUBLE PRECISION. The smaller singular value. Tiny but important 🎀
• SSMAX — SSMAX is DOUBLE PRECISION. The larger singular value. Big singular value energy 👑

🌸 Author

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

💀 Further Details

These caveats are keeping it real, bestie — no skipping them 🙈

• Barring over/underflow, all output quantities are correct to within a few units in the last place (ulps), even in the absence of a guard digit in addition/subtraction.
• In IEEE arithmetic, the code works correctly if one matrix element is infinite.
• Overflow will not occur unless the largest singular value itself overflows, or is within a few ulps of overflow.
• Underflow is harmless if underflow is gradual. Otherwise, results may correspond to a matrix modified by perturbations of size near the underflow threshold.

Definition at line 104 of file dlas2.f. ✨

👑 Author

This next one is the auto-gen author block, and it's literally:

Generated automatically by Doxygen for LAPACK from the source code.

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Cute sign-off time: the footer tea is LAPACK, Version 3.12.0, and page SRC/dlas2.f(3). There's no date shown on this one, so no fake date, bestie — just that source/version energy 💜🫶