SRC/sorgrq.f(3)

📦
version 3.12.1 · 7 versions
, in arch rolling

💖 SRC/sorgrq.f 💖

okay so this is the SRC/sorgrq.f(3) page from the Library Functions Manual — and yes, bestie, the whole thing is about SORGRQ, and it's giving ✨ linear algebra main character energy ✨.

🌸 NAME 🌸

SRC/sorgrq.f — that's the page name. The routine living inside is SORGRQ, and it's lowkey iconic.

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

  • subroutine sorgrq (m, n, k, a, lda, tau, work, lwork, info) — SORGRQ

🦋 Function/Subroutine Documentation 🦋

subroutine sorgrq (integer m, integer n, integer k, real, dimension( lda, * ) a, integer lda, real, dimension( * ) tau, real, dimension( * ) work, integer lwork, integer info)
    SORGRQ

The routine is SORGRQ, obviously. 💅

💜 Purpose 💜

SORGRQ generates an M-by-N real matrix Q with orthonormal rows. That Q is defined as the last M rows of a product of K elementary reflectors of order N:

Q  =  H(1) H(2) . . . H(k)

...exactly as returned by SGERQF. No cap. 🫶

🎀 Parameters 🎀

  • M — M is INTEGER. It's the number of rows of the matrix Q. M >= 0.
  • N — N is INTEGER. It's the number of columns of the matrix Q. N >= M.
  • K — K is INTEGER. It's the number of elementary reflectors whose product defines the matrix Q. M >= K >= 0.
  • A — A is REAL array, dimension (LDA,N). On entry, the (m-k+i)-th row must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by SGERQF in the last k rows of its array argument A. On exit, it's the M-by-N matrix Q. Slay. ✨
  • LDA — LDA is INTEGER. It's the first dimension of the array A. LDA >= max(1,M).
  • TAU — TAU is REAL array, dimension (K). TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SGERQF.
  • WORK — WORK is REAL array, dimension (MAX(1,LWORK)). On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
  • LWORK — LWORK is INTEGER. It's 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. Important bestie behavior. 💅

  • INFO — INFO is INTEGER. Exit codes are = 0: successful exit and < 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 🔥

Definition at line 127 of file sorgrq.f.

🧚 Author 🧚

Generated automatically by Doxygen for LAPACK from the source code.

And that's the tea, bestie: LAPACK Version 3.12.0 · SRC/sorgrq.f(3) · date: not listed on this page, but the routine still ate. 🎀💖

📦 where this page comes from