SRC/dorgqr.f(3)

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version 3.12.1 · 7 versions
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🎀 SRC/dorgqr.f(3) 🎀

okay so you've pulled up the SRC/dorgqr.f(3) page from the Library Functions Manual, bestie. It's giving "LAPACK subroutine docs but make it cute." Here's the whole thing, no skipped params, no cap. 💅

💖 NAME 💖

SRC/dorgqr.f

✨ SYNOPSIS ✨

Functions/Subroutines

  • subroutine dorgqr (m, n, k, a, lda, tau, work, lwork, info) — DORGQR

🦋 Function/Subroutine Documentation 🦋

subroutine dorgqr (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)

DORGQR

🌸 Purpose 🌸

Bestie, here's the whole point: DORGQR 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. ✨

🎀 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.

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 (MAX(1,LWORK)). On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

LWORK

LWORK is INTEGER. The dimension of the array WORK. LWORK >= max(1,N). For optimum performance LWORK >= N*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.

INFO

INFO is INTEGER

  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument has an illegal value

💜 Author 💜

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

⭐ Definition at line 127 of file dorgqr.f. ⭐

Definition at line 127 of file dorgqr.f.

📝 Author 📝

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okay bye bestie 🫶 — this footer energy is LAPACK Version 3.12.0, source SRC/dorgqr.f(3). The original doesn't give a date, so I'm not inventing one. Periodt. 💖

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