SRC/DEPRECATED/sgelqs.f(3)

📦
version 3.12.1 · 3 versions
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🎀 NAME 🎀

Hey bestie! We're looking at the sgelqs.f(3) page from LAPACK's Library Functions Manual, and the actual file is SRC/DEPRECATED/sgelqs.f. That's the name, and honestly it's giving "deprecated but still iconic" energy. 💅

✨ SYNOPSIS ✨

Functions/Subroutines

  • subroutine sgelqs (m, n, nrhs, a, lda, tau, b, ldb, work, lwork, info) — this is SGELQS, the main character of this page.
subroutine sgelqs (integer m, integer n, integer nrhs, real, dimension( lda,
* ) a, integer lda, real, dimension( * ) tau, real, dimension( ldb, * )
b, integer ldb, real, dimension( lwork ) work, integer lwork, integer
info)

SGELQS 🫶

💖 Function/Subroutine Documentation 💖

subroutine sgelqs (integer m, integer n, integer nrhs, real, dimension( lda,
* ) a, integer lda, real, dimension( * ) tau, real, dimension( ldb, * )
b, integer ldb, real, dimension( lwork ) work, integer lwork, integer
info)

SGELQS ✨

🌸 Purpose 🌸

Okay so this routine computes a minimum-norm solution:

min || A*X - B ||

using the LQ factorization:

A = L*Q

computed by SGELQF. No cap, that's the whole purpose. 💖

🦋 Parameters 🦋

  • M — M is INTEGER. The number of rows of the matrix A. M >= 0.
  • N — N is INTEGER. The number of columns of the matrix A. N >= M >= 0.
  • NRHS — NRHS is INTEGER. The number of columns of B. NRHS >= 0.
  • A — A is REAL array, dimension (LDA,N). Details of the LQ factorization of the original matrix A as returned by SGELQF.
  • LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= M.
  • TAU — TAU is REAL array, dimension (M). Details of the orthogonal matrix Q.
  • B — B is REAL array, dimension (LDB,NRHS). On entry, the m-by-nrhs right hand side matrix B. On exit, the n-by-nrhs solution matrix X.
  • LDB — LDB is INTEGER. The leading dimension of the array B. LDB >= N.
  • WORK — WORK is REAL array, dimension (LWORK).
  • LWORK — LWORK is INTEGER. The length of the array WORK. LWORK must be at least NRHS, and should be at least NRHS*NB, where NB is the block size for this environment.
  • INFO — INFO is 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 119 of file sgelqs.f.

🌈 Author 🌈

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mwah 💋 this cutie is from LAPACK Version 3.12.0, page SRC/DEPRECATED/sgelqs.f(3), and that's the whole sign-off. 🫶🎀

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