DGEMLQ(3)

💖 DGEMLQ(3) 💖

okay so this is the Library Functions Manual page for DGEMLQ(3) — header-path energy: /home/abui...RC/dgemlq.f(3). Bestie, it’s a LAPACK routine page, and we’re about to read it like a group chat, but every fact stays exactly where it belongs. No cap. 💅

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🌸 NAME 🌸

The full name is literally this file path:

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

That’s not a typo, it’s the NAME section being extra. 🎀

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🦋 SYNOPSIS 🦋

Functions/Subroutines

subroutine DGEMLQ (side, trans, m, n, k, a, lda, t, tsize, c, ldc, work,
    lwork, info)

DGEMLQ — that’s the function/subroutine in question, bestie. ✨

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🎀 Function/Subroutine Documentation 🎀

🧚 subroutine DGEMLQ 🧚

Detailed signature:

subroutine DGEMLQ (character side, character trans, integer m, integer n,
    integer k, double precision, dimension( lda, * ) a, integer lda, double
    precision, dimension( * ) t, integer tsize, double precision, dimension(
    ldc, * ) c, integer ldc, double precision, dimension( * ) work, integer
    lwork, integer info)

DGEMLQ.

✨ Purpose ✨

DGEMLQ overwrites the general real M-by-N matrix C with:

                    SIDE = 'L'     SIDE = 'R'
    TRANS = 'N':      Q * C          C * Q
    TRANS = 'T':      Q**T * C       C * Q**T

where Q is a real orthogonal matrix defined as the product of blocked elementary reflectors computed by short wide LQ factorization (DGELQ).

💅 Parameters 💅

• SIDE — SIDE is CHARACTER*1. The vibes are:
  • = 'L': apply Q or Q**T from the Left;
  • = 'R': apply Q or Q**T from the Right.
• TRANS — TRANS is CHARACTER*1. The choices:
  • = 'N': No transpose, apply Q;
  • = 'T': Transpose, apply Q**T.
• M — M is INTEGER. The number of rows of the matrix A. M >=0.
• N — N is INTEGER. The number of columns of the matrix C. N >= 0.
• K — K is INTEGER. The number of elementary reflectors whose product defines the matrix Q. If SIDE = 'L', M >= K >= 0; if SIDE = 'R', N >= K >= 0.
• A — A is DOUBLE PRECISION array, dimension (LDA,M) if SIDE = 'L', (LDA,N) if SIDE = 'R'. Part of the data structure to represent Q as returned by DGELQ.
• LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= max(1,K).
• T — T is DOUBLE PRECISION array, dimension (MAX(5,TSIZE)). Part of the data structure to represent Q as returned by DGELQ.
• TSIZE — TSIZE is INTEGER. The dimension of the array T. TSIZE >= 5.
• C — C is DOUBLE PRECISION array, dimension (LDC,N). On entry, the M-by-N matrix C. On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q.
• LDC — LDC is INTEGER. The leading dimension of the array C. LDC >= max(1,M).
• WORK — (workspace) DOUBLE PRECISION array, dimension (MAX(1,LWORK)).
• LWORK — LWORK is INTEGER. The dimension of the array WORK. If LWORK = -1, then a workspace query is assumed. The routine only calculates the size of the WORK array, returns this value as WORK(1), and no error message related to WORK is issued by XERBLA.
• INFO — INFO is INTEGER. The exit-status tea:
  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument had an illegal value

👑 Author 👑

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

🔥 Further Details 🔥

These details are particular for this LAPACK implementation. Users should not take them for granted. These details may change in the future, and are not likely true for another LAPACK implementation. These details are relevant if one wants to try to understand the code. They are not part of the interface.

In this version, bestie:

• T(2): row block size (MB)
• T(3): column block size (NB)
• T(6:TSIZE): data structure needed for Q, computed by DLASWLQ or DGELQT

Depending on the matrix dimensions M and N, and row and column block sizes MB and NB returned by ILAENV, DGELQ will use either DLASWLQ (if the matrix is wide-and-short) or DGELQT to compute the LQ factorization.

This version of DGEMLQ will use either DLAMSWLQ or DGEMLQT to multiply matrix Q by another matrix.

Further Details in DLAMSWLQ or DGEMLQT.

Definition at line 171 of file dgemlq.f.

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🧚 Author 🧚

Generated automatically by Doxygen for LAPACK from the source code.

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okay that’s the page, bestie. Cute sign-off: source/version is LAPACK Version 3.12.0, and the footer path is /home/abui...RC/dgemlq.f(3). The footer doesn’t list a date, so I’m not inventing one — no fake facts, periodt. 💅✨