sgetrf.f(3)

💅 sgetrf.f(3) — LAPACK, bestie ✨

okay so this is a page straight out of the LAPACK manual, and it's about sgetrf.f — yes that's the filename, yes it's giving "my friend who does linear algebra for fun" energy, and yes we're gonna get into it 🫶

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✨ NAME ✨

sgetrf.f — the file, the myth, the legend 🎀

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🌸 SYNOPSIS 🌸

Functions/Subroutines

subroutine sgetrf (M, N, A, LDA, IPIV, INFO)

SGETRF VARIANT: Crout Level 3 BLAS version of the algorithm. periodt 💅

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🦋 Function/Subroutine Documentation 🦋

subroutine sgetrf (integer M, integer N, real, dimension( lda, * ) A, integer LDA, integer, dimension( * ) IPIV, integer INFO)

SGETRF VARIANT: Crout Level 3 BLAS version of the algorithm. (yes, this is the Crout Level 3 BLAS one — that detail matters, don't @ me)

🎯 Purpose:

SGETRF computes an LU factorization of a general M-by-N matrix A using partial pivoting with row interchanges. no cap, that's the whole job 🔥

The factorization has the form

A = P * L * U

where P is a permutation matrix, L is lower triangular with unit diagonal elements (lower trapezoidal if m > n), and U is upper triangular (upper trapezoidal if m < n).

This is the Crout Level 3 BLAS version of the algorithm. (yes, again. it's iconic like that 👑)

🌈 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 >= 0.

• A

A is REAL array, dimension (LDA,N) On entry, the M-by-N matrix to be factored. On exit, the factors L and U from the factorization A = P*L*U; the unit diagonal elements of L are not stored. (they're implied, bestie, it's a whole thing 💀)

• LDA

LDA is INTEGER The leading dimension of the array A. LDA >= max(1,M).

• IPIV

IPIV is INTEGER array, dimension (min(M,N)) The pivot indices; for 1 <= i <= min(M,N), row i of the matrix was interchanged with row IPIV(i). so that's who swapped with who, receiving all the receipts 🧚

• INFO

INFO is INTEGER

= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value
> 0:  if INFO = i, U(i,i) is exactly zero. The factorization
      has been completed, but the factor U is exactly
      singular, and division by zero will occur if it is used
      to solve a system of equations.

⚠️ okay real talk: if INFO > 0, the factorization did finish but U is exactly singular — so if you try to solve a system of equations with it, division by zero is gonna happen. that's not a vibe. check your INFO, bestie 😭

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💜 Author: 💜

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

(absolute icons, all of them 🌟)

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🍓 Date: 🍓

December 2016

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⭐ Definition at line 102 of file VARIANTS/lu/CR/sgetrf.f. ⭐

like, literally line 102, in VARIANTS/lu/CR/sgetrf.f — go look, iykyk 🌸

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👑 Author (the meta one) 👑

Generated automatically by Doxygen for LAPACK from the source code. (Doxygen really said "i'll write the docs, you go touch grass" 🙈)

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and that's the whole page!! 💖 Version 3.8.0, dated Tue Nov 14 2017 — mwah, slay, see u in the next manpage bestie 🎀✨🦋