getf2(3)

📦
version 3.12.1 · 9 versions
, in arch rolling

💅 NAME 💅

okay so bestie, welcome to getf2 — from the Library Functions Manual, section 3, no less 👑 — it's getf2: triangular factor panel, level 2. that's the whole name. short, iconic, does exactly what it says on the tin. 🫶

✨ SYNOPSIS ✨

🌸 Functions 🌸

  • 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). 💖
  • subroutine dgetf2 (m, n, a, lda, ipiv, info) — DGETF2 computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm). 💜
  • subroutine sgetf2 (m, n, a, lda, ipiv, info) — SGETF2 computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm). 🦋
  • subroutine zgetf2 (m, n, a, lda, ipiv, info) — ZGETF2 computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm). 🎀

🌈 Detailed Description 🌈

literally just vibes and function docs below, bestie — every routine gets its own little moment, so scroll to the precision you need. no cap, they're all basically the same routine wearing different data-type outfits. 💀

🎀 Function 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).

💖 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.
!>

🧚 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.
!>
  • 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).
!>
  • 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.
!>
🫶 okay real talk for a sec: INFO > 0 means the factorization finished but U is exactly singular — so if you go solve a system with it, division by zero is gonna happen. no cap, that's a bad time. 😭

👑 Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 107 of file cgetf2.f.

⭐ subroutine dgetf2 (integer m, integer n, double precision, dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, integer info)

DGETF2 computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm).

💖 Purpose:

!>
!> DGETF2 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.
!>

🧚 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 DOUBLE PRECISION 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.
!>
  • 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).
!>
  • 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.
!>

👑 Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 107 of file dgetf2.f.

⭐ subroutine sgetf2 (integer m, integer n, real, dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, integer info)

SGETF2 computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm).

💖 Purpose:

!>
!> SGETF2 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.
!>

🧚 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.
!>
  • 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).
!>
  • 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.
!>

👑 Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 107 of file sgetf2.f.

⭐ subroutine zgetf2 (integer m, integer n, complex*16, dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, integer info)

ZGETF2 computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm).

💖 Purpose:

!>
!> ZGETF2 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.
!>

🧚 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*16 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.
!>
  • 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).
!>
  • 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.
!>

👑 Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 107 of file zgetf2.f.

🦋 Author 🦋

Generated automatically by Doxygen for LAPACK from the source code. (yes bestie, a robot wrote this one, and honestly? it ate. 🤖✨)

and that's the whole page!! 💖 shoutout to LAPACK, Version 3.12.0, for serving us this absolute icon of a routine — mwah, love u, bye 🫶🎀

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