DORGLQ(3)

✨ DORGLQ(3) ✨

okay so bestie, welcome to the DORGLQ glow-up page 💅 this is a LAPACK manual page, specifically for the file

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

yes that is literally the whole NAME section, it's giving "my name is my address" energy and honestly? iconic 🎀

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💖 SYNOPSIS 💖

Functions/Subroutines

• subroutine DORGLQ (m, n, k, a, lda, tau, work, lwork, info) — DORGLQ 🦋

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🌸 Function/Subroutine Documentation 🌸

subroutine DORGLQ (integer m, integer n, integer k, double precision,
     dimension( lda, * ) a, integer lda, double precision, dimension( * )
     tau, double precision, dimension( * ) work, integer lwork, integer info)

DORGLQ 👑

⭐ Purpose ⭐

!> !> DORGLQ generates an M-by-N real matrix Q with orthonormal rows, !> which is defined as the first M rows of a product of K elementary !> reflectors of order N !> !> Q = H(k) . . . H(2) H(1) !> !> as returned by DGELQF. !>

so basically it builds you a real M-by-N matrix Q whose rows are orthonormal (slay), and Q is the first M rows of that big product of K elementary reflectors of order N, the ones DGELQF handed you earlier 🫶 no cap, that's the whole vibe.

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🦋 Parameters 🦋

• M

!> M is INTEGER !> The number of rows of the matrix Q. M >= 0. !>

the row count for Q, and M >= 0 — can't have negative rows bestie 😭

• N

!> N is INTEGER !> The number of columns of the matrix Q. N >= M. !>

the column count for Q, with N >= M (that's a whole constraint, respect it 💀)

• K

!> K is INTEGER !> The number of elementary reflectors whose product defines the !> matrix Q. M >= K >= 0. !>

how many elementary reflectors are in the product — M >= K >= 0 periodt.

• A

!> A is DOUBLE PRECISION array, dimension (LDA,N) !> On entry, the i-th row must contain the vector which defines !> the elementary reflector H(i), for i = 1,2,...,k, as returned !> by DGELQF in the first k rows of its array argument A. !> On exit, the M-by-N matrix Q. !>

on entry, row i holds the vector defining H(i) for i = 1,2,...,k, exactly as DGELQF gave it back in the first k rows of its A. on exit? boom, it's the M-by-N matrix Q. glow-up complete ✨

• LDA

!> LDA is INTEGER !> The first dimension of the array A. LDA >= max(1,M). !>

the first dimension of A, and LDA >= max(1,M) — lowercase max because Fortran, we don't question it 💅

• TAU

!> TAU is DOUBLE PRECISION array, dimension (K) !> TAU(i) must contain the scalar factor of the elementary !> reflector H(i), as returned by DGELQF. !>

TAU(i) carries the scalar factor of H(i), again straight from DGELQF 🎀

• WORK

!> WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)) !> On exit, if INFO = 0, WORK(1) returns the optimal LWORK. !>

the workspace, size MAX(1,LWORK). on exit, if INFO = 0, then WORK(1) tells you the optimal LWORK — a little gift 🎁

• LWORK

!> LWORK is INTEGER !> The dimension of the array WORK. LWORK >= max(1,M). !> For optimum performance LWORK >= M*NB, where NB is !> the optimal blocksize. !> !> If LWORK = -1, then a workspace query is assumed; the routine !> only calculates the optimal size of the WORK array, returns !> this value as the first entry of the WORK array, and no error !> message related to LWORK is issued by XERBLA. !>

size of WORK, needs LWORK >= max(1,M). for optimum performance you want LWORK >= M*NB where NB is the optimal blocksize 🔥 and bestie, listen: if LWORK = -1 it's a workspace query — it only computes the optimal WORK size, drops it in the first entry of WORK, and XERBLA issues no error message about LWORK. so cute of it.

• INFO

!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -i, the i-th argument has an illegal value !>

= 0 means successful exit 🎉 and < 0 means if INFO = -i, the i-th argument had an illegal value 🙈

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👑 Author 👑

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

legendary lineup fr fr 🌈

Definition at line 126 of file dorglq.f.

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💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code.

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and that's the whole page bestie, hope you understood it, mwah 🫶

LAPACK · Version 3.12.0 · /home/abui...RC/dorglq.f(3) — ty for reading, go write some orthonormal rows, ily 💖✨🎀