DORG2R(3)

💅 NAME 💅

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dorg2r.f

okay so bestie, that's the whole name, yes it's a whole file path, yes it's a lot, but that's literally what this page is about 🫶 it's a LAPACK library functions manual situation, and this is the dorg2r.f girlie herself.

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✨ SYNOPSIS ✨

🦋 Functions/Subroutines

subroutine DORG2R (m, n, k, a, lda, tau, work, info)

DORG2R generates all or part of the orthogonal matrix Q from a QR factorization determined by sgeqrf (unblocked algorithm).

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👑 Function/Subroutine Documentation 👑

subroutine DORG2R (integer m, integer n, integer k, double precision,
    dimension( lda, * ) a, integer lda, double precision, dimension( * )
    tau, double precision, dimension( * ) work, integer info)

DORG2R generates all or part of the orthogonal matrix Q from a QR factorization determined by sgeqrf (unblocked algorithm).

🎀 Purpose:

!>
!> DORG2R generates an m by n real matrix Q with orthonormal columns,
!> which is defined as the first n columns of a product of k elementary
!> reflectors of order m
!>
!>       Q  =  H(1) H(2) . . . H(k)
!>
!> as returned by DGEQRF.
!>

so like, it builds Q for you — the first n columns of that big ol' product of k elementary reflectors of order m — exactly as DGEQRF handed them back. no cap, it's giving "cleanup crew for your QR factorization" energy 🔥

🌸 Parameters

• M — M is INTEGER, the number of rows of the matrix Q. M >= 0.
• N — N is INTEGER, the number of columns of the matrix Q. M >= N >= 0.
• K — K is INTEGER, the number of elementary reflectors whose product defines the matrix Q. N >= K >= 0.
• A — A is DOUBLE PRECISION array, dimension (LDA,N). On entry, the i-th column must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by DGEQRF in the first k columns of its array argument A. On exit, the m-by-n matrix Q. 👑 like she literally transforms in front of you, main character energy.
• LDA — LDA is INTEGER, the first dimension of the array A. LDA >= max(1,M).
• TAU — TAU is DOUBLE PRECISION array, dimension (K). TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by DGEQRF.
• WORK — WORK is DOUBLE PRECISION array, dimension (N). that's it, that's the whole description, go off workspace 💀
• INFO — INFO is INTEGER.
  • = 0: successful exit 🎉
  • < 0: if INFO = -i, the i-th argument has an illegal value 🙈

ok but fr fr if you see INFO < 0 bestie, one of your arguments is illegal and you gotta go figure out which one. the code is literally telling you the index. read it. iykyk 💅

⭐ Author

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

Definition at line 113 of file dorg2r.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! 🎀✨

this iconic little number is LAPACK Version 3.12.0, and the footer timestamp situation is /home/abui...RC/dorg2r.f(3) — slay, go forth and orthonormalize 💜🦋