SRC/dgemlqt.f(3)

🌸 NAME

SRC/dgemlqt.f — from the Library Functions Manual, bestie! This is the DGEMLQT page, and it's giving serious linear-algebra main-character energy. 💅✨

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✨ SYNOPSIS ✨

Functions/Subroutines

subroutine dgemlqt (side, trans, m, n, k, mb, v, ldv, t, ldt, c, ldc,
    work, info)

DGEMLQT — that's the routine, no cap. 🫶

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🫶 Function/Subroutine Documentation 🫶

Here's the full signature, character-for-character, because we do not play about details:

subroutine dgemlqt (character side, character trans, integer m, integer n,
    integer k, integer mb, double precision, dimension( ldv, * ) v, integer
    ldv, double precision, dimension( ldt, * ) t, integer ldt, double
    precision, dimension( ldc, * ) c, integer ldc, double precision,
    dimension( * ) work, integer info)

DGEMLQT ✨

💖 Purpose 💖

okay so here's the vibe: DGEMLQT 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 K elementary reflectors:

Q = H(1) H(2) . . . H(K) = I - V T V**T

generated using the compact WY representation as returned by DGELQT.

Q is of order M if SIDE = 'L' and of order N if SIDE = 'R'. 🌈

🎀 Parameters 🎀

• SIDE — CHARACTER*1. = 'L': apply Q or Q**T from the Left; = 'R': apply Q or Q**T from the Right. Left or right, she's applying. 👑
• TRANS — CHARACTER*1. = 'N': No transpose, apply Q; = 'C': Transpose, apply Q**T. Keep that exactly as written, bestie. 🦋
• M — INTEGER. The number of rows of the matrix C. M >= 0.
• N — INTEGER. The number of columns of the matrix C. N >= 0.
• K — INTEGER. The number of elementary reflectors whose product defines the matrix Q. If SIDE = 'L', M >= K >= 0; if SIDE = 'R', N >= K >= 0.
• MB — INTEGER. The block size used for the storage of T. K >= MB >= 1. This must be the same value of MB used to generate T in DGELQT. same-value energy, no substitutions. 🧚
• V — DOUBLE PRECISION array, dimension (LDV,M) if SIDE = 'L', (LDV,N) if SIDE = 'R'. The i-th row must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by DGELQT in the first K rows of its array argument A.
• LDV — INTEGER. The leading dimension of the array V. LDV >= max(1,K).
• T — DOUBLE PRECISION array, dimension (LDT,K). The upper triangular factors of the block reflectors as returned by DGELQT, stored as a MB-by-K matrix.
• LDT — INTEGER. The leading dimension of the array T. LDT >= MB.
• C — DOUBLE PRECISION array, dimension (LDC,N). On entry, the M-by-N matrix C. On exit, C is overwritten by Q C, Q**T C, C Q**T or C Q. she gets rewritten, periodt. 💀
• LDC — INTEGER. The leading dimension of the array C. LDC >= max(1,M).
• WORK — DOUBLE PRECISION array. The dimension of WORK is N*MB if SIDE = 'L', or M*MB if SIDE = 'R'.
• INFO — 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.

Definition at line 166 of file dgemlqt.f.

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🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

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okay that's the whole page, bestie — footer vibes: LAPACK Version 3.12.0, source page SRC/dgemlqt.f(3). mwah, bye 💖✨