DLARFY(3)

💖 DLARFY(3) — dlarfy.f(3) 💖

Manual name, front and center: dlarfy.f(3). This is from the Library Functions Manual, bestie.

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🌸 NAME 🌸

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/EIG/dlarfy.f

That’s the file this page is about, and yes, the manual name is dlarfy.f(3). Slay.

✨ SYNOPSIS ✨

🫶 Functions/Subroutines 🫶

• subroutine DLARFY (uplo, n, v, incv, tau, c, ldc, work) — the whole subroutine vibe. Also: DLARFY. Yes, that’s the name again. Iconic behavior.

🦋 Function/Subroutine Documentation 🦋

💫 DLARFY 💫

subroutine DLARFY (character uplo, integer n, double precision, dimension( *
       ) v, integer incv, double precision tau, double precision, dimension(
       ldc, * ) c, integer ldc, double precision, dimension( * ) work)

DLARFY — again, not a typo, that’s literally the name. 💅

🎀 Purpose 🎀

Okay so here’s the tea: DLARFY applies an elementary reflector, or Householder matrix, H, to an n x n symmetric matrix C, from both the left and the right. Both sides! Equal opportunity matrix transformation. 💖

H is represented in the form:

H = I - tau * v * v'

where tau is a scalar and v is a vector. Lowkey important.

If tau is zero, then H is taken to be the unit matrix. Periodt. ✨

🌸 Parameters 🌸

• UPLO — UPLO is CHARACTER*1. Specifies whether the upper or lower triangular part of the symmetric matrix C is stored. = 'U': Upper triangle, = 'L': Lower triangle.
• N — N is INTEGER. The number of rows and columns of the matrix C. N >= 0.
• V — V is DOUBLE PRECISION array, dimension (1 + (N-1)*abs(INCV)). The vector v as described above. Bestie, that dimension formula is giving main character energy.
• INCV — INCV is INTEGER. The increment between successive elements of v. INCV must not be zero. No cap, zero is not allowed here.
• TAU — TAU is DOUBLE PRECISION. The value tau as described above.
• C — C is DOUBLE PRECISION array, dimension (LDC, N). On entry, the matrix C. On exit, C is overwritten by H * C * H'. She gets transformed, literally.
• LDC — LDC is INTEGER. The leading dimension of the array C. LDC >= max( 1, N ).
• WORK — WORK is DOUBLE PRECISION array, dimension (N). The workspace, doing its little behind-the-scenes thing. 🫶

👑 Author 👑

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

Definition at line 107 of file dlarfy.f.

🌟 Author 🌟

Generated automatically by Doxygen for LAPACK from the source code.

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Footer sign-off, bestie: LAPACK Version 3.12.0, and the footer path is /home/abui...IG/dlarfy.f(3). 💖✨