DLARZB(3)

✨ DLARZB(3) ✨ — Library Functions Manual 💖

okay so welcome to the Library Functions Manual page for DLARZB(3), bestie. This is the LAPACK subroutine that applies a block reflector or its transpose to a general matrix, and we are keeping every single flag and dimension rule. No cap. 💅

📛 NAME

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dlarzb.f — yes, that is the full path from the original NAME section, character for character. 🫶

🌸 SYNOPSIS

Functions/Subroutines

• DLARZB — DLARZB applies a block reflector or its transpose to a general matrix.

subroutine DLARZB (side, trans, direct, storev, m, n, k, l, v, ldv, t,
    ldt, c, ldc, work, ldwork)

🧚 Function/Subroutine Documentation

subroutine DLARZB (...)

subroutine DLARZB (character side, character trans, character direct,
    character storev, integer m, integer n, integer k, integer l, double
    precision, dimension( ldv, * ) v, integer ldv, double precision,
    dimension( ldt, * ) t, integer ldt, double precision, dimension( ldc, *
    ) c, integer ldc, double precision, dimension( ldwork, * ) work, integer
    ldwork)

DLARZB applies a block reflector or its transpose to a general matrix.

🎯 Purpose:

okay so the purpose is literally: DLARZB applies a real block reflector H or its transpose H**T to a real distributed M-by-N C from the left or the right. Currently, only STOREV = 'R' and DIRECT = 'B' are supported. That is the whole plot. 💀

⚠️ Caveat that matters: currently only STOREV = 'R' and DIRECT = 'B' are supported. Everything else is not supported yet.

🛠️ Parameters

• SIDE — SIDE is CHARACTER*1. = 'L': apply H or H**T from the Left; = 'R': apply H or H**T from the Right. 🫶
• TRANS — TRANS is CHARACTER*1. = 'N': apply H (No transpose); = 'C': apply H**T (Transpose). ✨
• DIRECT — DIRECT is CHARACTER*1. Indicates how H is formed from a product of elementary reflectors. = 'F': H = H(1) H(2) . . . H(k) (Forward, not supported yet); = 'B': H = H(k) . . . H(2) H(1) (Backward). 🔥
• STOREV — STOREV is CHARACTER*1. Indicates how the vectors which define the elementary reflectors are stored: = 'C': Columnwise (not supported yet); = 'R': Rowwise. 🌈
• M — M is INTEGER. The number of rows of the matrix C.
• N — N is INTEGER. The number of columns of the matrix C.
• K — K is INTEGER. The order of the matrix T (= the number of elementary reflectors whose product defines the block reflector).
• L — L is INTEGER. The number of columns of the matrix V containing the meaningful part of the Householder reflectors. If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0.
• V — V is DOUBLE PRECISION array, dimension (LDV,NV). If STOREV = 'C', NV = K; if STOREV = 'R', NV = L.
• LDV — LDV is INTEGER. The leading dimension of the array V. If STOREV = 'C', LDV >= L; if STOREV = 'R', LDV >= K.
• T — T is DOUBLE PRECISION array, dimension (LDT,K). The triangular K-by-K matrix T in the representation of the block reflector.
• LDT — LDT is INTEGER. The leading dimension of the array T. LDT >= K.
• C — C is DOUBLE PRECISION array, dimension (LDC,N). On entry, the M-by-N matrix C. On exit, C is overwritten by H*C or H**T*C or C*H or C*H**T.
• LDC — LDC is INTEGER. The leading dimension of the array C. LDC >= max(1,M).
• WORK — WORK is DOUBLE PRECISION array, dimension (LDWORK,K).
• LDWORK — LDWORK is INTEGER. The leading dimension of the array WORK. If SIDE = 'L', LDWORK >= max(1,N); if SIDE = 'R', LDWORK >= max(1,M).

👑 Author

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

💖 Contributors:

A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA

💜 Further Details:

The original block is just:

!>

No extra lore, iconic minimalism. 🎀

📌 Definition at line 181 of file dlarzb.f.

📜 Author

Generated automatically by Doxygen for LAPACK from the source code.

Cute sign-off: the footer says LAPACK Version 3.12.0 and /home/abui...RC/dlarzb.f(3) — no date line in sight, that's the whole footer vibe. Bye bestie, go apply that block reflector or its transpose. 💅💖