SGEMLQ(3)

💅 SGEMLQ(3) 💅

From the Library Functions Manual, bestie. This is the LAPACK page for SGEMLQ, and we’re gonna read it together like the group chat is watching. 🫶

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🎀 NAME 🎀

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

That’s the file path, character for character. No cap. ✨

🦋 SYNOPSIS 🦋

✨ Functions/Subroutines ✨

Functions/Subroutines
    subroutine SGEMLQ (side, trans, m, n, k, a, lda, t, tsize, c, ldc, work,
        lwork, info)
        SGEMLQ

🫶 Function/Subroutine Documentation 🫶

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

SGEMLQ

🌈 Purpose 🌈

Okay so SGEMLQ 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 (SGELQ). 💖

💖 Parameters 💖

• SIDE — SIDE is CHARACTER*1; = 'L': apply Q or Q**T from the Left; = 'R': apply Q or Q**T from the Right.
• TRANS — TRANS is CHARACTER*1; = '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 REAL array, dimension (LDA,M) if SIDE = 'L', (LDA,N) if SIDE = 'R'; Part of the data structure to represent Q as returned by DGELQ. (yes, that says DGELQ, bestie — we keep it exactly as written 💅)
• LDA — LDA is INTEGER; The leading dimension of the array A. LDA >= max(1,K).
• T — T is REAL array, dimension (MAX(5,TSIZE)). Part of the data structure to represent Q as returned by SGELQ.
• TSIZE — TSIZE is INTEGER; The dimension of the array T. TSIZE >= 5.
• C — C is REAL 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) REAL 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; = 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:

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

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

This version of SGEMLQ will use either SLAMSWLQ or SGEMLQT to multiply matrix Q by another matrix.

Further Details in SLAMSWLQ or SGEMLQT.

Definition at line 170 of file sgemlq.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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Okay bestie, that’s the whole page. 💖 LAPACK Version 3.12.0, source footer path /home/abui...RC/sgemlq.f(3), and the date isn’t listed in that footer — no cap. 🎀