/home/abui...RC/dlas2.f(3)

📦 version 3.12.0, in opensuse-leap 16.0

💖 NAME 💖

bestie, this page is /home/abui...RC/dlas2.f(3) from the Library Functions Manual — yes, we’re doing LAPACK math today, and it’s giving main-character linear algebra energy. ✨ The actual source file is:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dlas2.f

🌈 SYNOPSIS 🌈

✨ Functions/Subroutines ✨

subroutine DLAS2 (f, g, h, ssmin, ssmax)

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

🎀 Function/Subroutine Documentation 🎀

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. Periodt. 💅

💫 Purpose 💫

okay so DLAS2 computes the singular values of the 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 plot, and it ate. 🦋

🌸 Parameters 🌸

  • F — F is DOUBLE PRECISION; the (1,1) element of the 2-by-2 matrix. 🍓
  • G — G is DOUBLE PRECISION; the (1,2) element of the 2-by-2 matrix. 🍓
  • H — H is DOUBLE PRECISION; the (2,2) element of the 2-by-2 matrix. 🍓
  • SSMIN — SSMIN is DOUBLE PRECISION; the smaller singular value. 💖
  • SSMAX — SSMAX is DOUBLE PRECISION; the larger singular value. 💖

👑 Author 👑

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

🔥 Further Details 🔥

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. no cap, that’s the accuracy vibe. ✨

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 🧚

Generated automatically by Doxygen for LAPACK from the source code. 💻

💜 cute little sign-off: this is LAPACK, Version 3.12.0, and the footer path is /home/abui...RC/dlas2.f(3). The footer doesn’t show a date, bestie — just source/version and path. 🎀

📦 where this page comes from