SRC/DEPRECATED/cgeqrs.f(3)

📦
version 3.12.1 · 2 versions
, in arch rolling

💅 SRC/DEPRECATED/cgeqrs.f — from the Library Functions Manual 🎀

okay so bestie, welcome to cgeqrs ✨ this little icon lives in the LAPACK library functions manual, and yes the path literally says DEPRECATED — the filename is telling on itself, iykyk 🙈 but she still eats, so let's get into it.

✨ SYNOPSIS ✨

Functions/Subroutines

  • subroutine cgeqrs (m, n, nrhs, a, lda, tau, b, ldb, work, lwork, info) — the one and only CGEQRS 💖

🌸 Function/Subroutine Documentation 🌸

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

CGEQRS 👑

🦋 Purpose 🦋

So what does she actually do? She solves the least squares problem

min || A*X - B ||

using the QR factorization

A = Q*R

computed by CGEQRF. That's it, that's the whole vibe 💅 (no cap, CGEQRF did the heavy lifting first — she's just here to finish the job).

🎀 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. M >= N >= 0. 🌸 (yes, both bounds, she's picky and she's right)

NRHS

NRHS is INTEGER. The number of columns of B. NRHS >= 0. 💜

A

A is COMPLEX array, dimension (LDA,N). Details of the QR factorization of the original matrix A as returned by CGEQRF. 🧚 (so do NOT roll up in here with a fresh matrix, she wants the factorization output)

LDA

LDA is INTEGER. The leading dimension of the array A. LDA >= M. 🔥

TAU

TAU is COMPLEX array, dimension (N). Details of the orthogonal matrix Q. ✨

B

B is COMPLEX array, dimension (LDB,NRHS). On entry, the m-by-nrhs right hand side matrix B. On exit, the n-by-nrhs solution matrix X. 👑 (she goes in as B and comes out as X, main character transformation fr fr)

LDB

LDB is INTEGER. The leading dimension of the array B. LDB >= M. 🫶

WORK

WORK is COMPLEX 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. 💀 (don't skimp on the workspace bestie, she said should be NRHS*NB for a reason)

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 cgeqrs.f. 📌

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code. 🤖 (not a human, just the doc goblin doing its thing)

ok that's the whole page!! every flag accounted for, every bound preserved, nothing skipped 🫶

LAPACK — Version 3.12.0 — and the file is SRC/DEPRECATED/cgeqrs.f(3), mwah 💋 slay, bye bestie 🦋✨

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