SRC/dlarf.f(3)

💅 SRC/dlarf.f 💅

okay bestie, welcome to the Library Functions Manual page for SRC/dlarf.f. this is the dlarf entry, and it's literally about applying a real elementary reflector to a real general rectangular matrix. it's giving linear algebra main character energy, no cap. highkey obsessed. 🫶✨

---

✨ NAME ✨

SRC/dlarf.f

short, iconic, to the point. periodt. 💖

🌸 SYNOPSIS 🌸

🧚 Functions/Subroutines 🧚

subroutine dlarf (character side, integer m, integer n, double precision,
       dimension( * ) v, integer incv, double precision tau, double precision,
       dimension( ldc, * ) c, integer ldc, double precision, dimension( * )
       work)

• dlarf — DLARF applies an elementary reflector to a general rectangular matrix. 💫

🎀 Function/Subroutine Documentation 🎀

🦋 subroutine dlarf 🦋

subroutine dlarf (character side, integer m, integer n, double precision, dimension( * ) v, integer incv, double precision tau, double precision, dimension( ldc, * ) c, integer ldc, double precision, dimension( * ) work)

DLARF applies an elementary reflector to a general rectangular matrix. yes bestie, that's the whole gig. 🫡

Purpose

okay so the real tea: DLARF applies a real elementary reflector H to a real m by n matrix C, from either the left or the right. H is represented in the form

      H = I - tau * v * v**T

where tau is a real scalar and v is a real vector. 🧚

if tau = 0, then H is taken to be the unit matrix. iconic behavior, honestly. 💅

Parameters

• SIDE — SIDE is CHARACTER*1. = 'L': form H * C; = 'R': form C * H. choose your fighter, bestie. 🌈
• M — M is INTEGER. it tells you how many rows C has. rows era. 📏
• N — N is INTEGER. it tells you how many columns C has. columns said "me too". 📐
• V — V is a DOUBLE PRECISION array, dimension (1 + (M-1)*abs(INCV)) if SIDE = 'L' or (1 + (N-1)*abs(INCV)) if SIDE = 'R'. this is the vector v in the representation of H. V is not used if TAU = 0. 🍓
• INCV — INCV is INTEGER. the increment between elements of v. INCV <> 0. bestie, that's a hard requirement, not a suggestion. 🚨
• TAU — TAU is DOUBLE PRECISION. the value tau in the representation of H. 💫
• C — C is a DOUBLE PRECISION array, dimension (LDC,N). on entry, it's the m by n matrix C. on exit, C is overwritten by the matrix H * C if SIDE = 'L', or C * H if SIDE = 'R'. not me getting overwritten mid-page 😭
• LDC — LDC is INTEGER. the leading dimension of the array C. LDC >= max(1,M). another vibe check, another requirement. 👑
• WORK — WORK is a DOUBLE PRECISION array, dimension (N) if SIDE = 'L' or (M) if SIDE = 'R'. it's giving workspace realness. 🛠️

lowkey important: INCV <> 0 and LDC >= max(1,M) are constraints, bestie — don't skip them. and yes, C gets overwritten on exit. no cap. 💀

Author

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

those are the author credits, and they ate. 🫶

Definition at line 123 of file dlarf.f.

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code. (yes, that's the actual line, bestie.) 🧚

---

okay that's the whole page, fr fr! 💖 this footer is giving LAPACK Version 3.12.0 + SRC/dlarf.f(3) — date? not printed in this footer, so I'm not inventing one, iykyk. slay, bestie, periodt. 🎀✨