SRC/cgetf2.f(3)

💖 SRC/cgetf2.f 💖

okay so bestie, welcome to the glow-up era of SRC/cgetf2.f — it's a LAPACK source file page (yes, the manual name is literally Library Functions Manual), and honestly? she's iconic.

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✨ SYNOPSIS ✨

🎀 Functions/Subroutines

• subroutine cgetf2 (m, n, a, lda, ipiv, info) — CGETF2 computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm). slay.

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🌸 Function/Subroutine Documentation 🌸

subroutine cgetf2 (integer m, integer n, complex, dimension( lda, * ) a,
    integer lda, integer, dimension( * ) ipiv, integer info)

CGETF2 computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm). no cap, that's the whole vibe.

💜 Purpose:

!>
!> CGETF2 computes an LU factorization of a general m-by-n matrix A
!> using partial pivoting with row interchanges.
!>
!> 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 right-looking Level 2 BLAS version of the algorithm.
!>

so like, it's giving A = P * L * U energy: P is a permutation matrix, L is lower triangular with unit diagonal elements (lower trapezoidal when m > n), and U is upper triangular (upper trapezoidal when m < n). and bestie, it's the right-looking Level 2 BLAS version of the algorithm — iykyk. 🔥

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🦋 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 COMPLEX 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.
!>

on entry she's the m by n matrix to be factored; on exit you get the factors L and U from A = P*L*U. and note 📝: the unit diagonal elements of L are not stored — they're implied, we don't keep receipts.

• 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).
!>

the pivot indices, bestie. for 1 <= i <= min(M,N), row i of the matrix was interchanged with row IPIV(i). the way that row got swapped… main character behavior. 💅

• INFO

!>          INFO is INTEGER
!>          = 0: successful exit
!>          < 0: if INFO = -k, the k-th argument had an illegal value
!>          > 0: if INFO = k, U(k,k) 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.
!>

so: = 0 means successful exit 🎉. < 0 means if INFO = -k, the k-th argument had an illegal value 🚩. > 0 means if INFO = k, U(k,k) is exactly zero — the factorization has been completed, but the factor U is exactly singular, and division by zero will occur if it's used to solve a system of equations. 😭 that's the danger zone, fr fr, do not ignore that one.

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👑 Author

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

Definition at line 107 of file cgetf2.f.

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🌈 Author

Generated automatically by Doxygen for LAPACK from the source code. (the robots did this one, not me 🙈)

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okay bye bestie, love u! 🫶 this page hit different — it's LAPACK, Version 3.12.0, dated on the SRC/cgetf2.f(3) page. go factor something gorgeous. 💖✨🍓