getrf(3)

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version 3.12.1 · 9 versions
, in arch rolling

getrf(3) 🌈✨

okay so this is the getrf(3) page from the Library Functions Manual, and it is literally the LU-factorization bestie you call when you need A = P * L * U energy. 🎀

NAME 💖

getrf - getrf: triangular factor

SYNOPSIS 🦋

Functions

  • subroutine cgetrf (m, n, a, lda, ipiv, info) — CGETRF
  • subroutine dgetrf (m, n, a, lda, ipiv, info) — DGETRF
  • subroutine sgetrf (m, n, a, lda, ipiv, info) — SGETRF
  • subroutine zgetrf (m, n, a, lda, ipiv, info) — ZGETRF

Detailed Description ✨

The detailed description is basically “go read the function docs below, bestie” — and the function docs are right here. 🫶

Function Documentation 👑

subroutine cgetrf (integer m, integer n, complex, dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, integer info) — CGETRF 💅

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

Purpose 🌸

CGETRF computes an LU factorization of a general M-by-N matrix A using partial pivoting with row interchanges. No cap.

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). Iconic triangular behavior, honestly.

This is the right-looking Level 3 BLAS version of the algorithm. ⚡

Parameters 🧚

  • M — INTEGER. The number of rows of the matrix A. Constraint: M >= 0.
  • N — INTEGER. The number of columns of the matrix A. Constraint: N >= 0.
  • A — 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 — INTEGER. The leading dimension of the array A. Constraint: LDA >= max(1,M).
  • IPIV — 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 — 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.

Author 👑

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

Definition at line 107 of file cgetrf.f.

subroutine dgetrf (integer m, integer n, double precision, dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, integer info) — DGETRF 🔥

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

Purpose 🌈

DGETRF computes an LU factorization of a general M-by-N matrix A using partial pivoting with row interchanges. Same iconic algorithm energy, double-precision edition.

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 3 BLAS version of the algorithm. ⭐

Parameters 🍓

  • M — INTEGER. The number of rows of the matrix A. Constraint: M >= 0.
  • N — INTEGER. The number of columns of the matrix A. Constraint: N >= 0.
  • A — 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 — INTEGER. The leading dimension of the array A. Constraint: LDA >= max(1,M).
  • IPIV — 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 — 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.

Author 👑

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

Definition at line 107 of file dgetrf.f.

subroutine sgetrf (integer m, integer n, real, dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, integer info) — SGETRF 🎀

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

Purpose 💜

SGETRF computes an LU factorization of a general M-by-N matrix A using partial pivoting with row interchanges. Real ones, rise.

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 3 BLAS version of the algorithm. 🌟

Parameters 🦋

  • M — INTEGER. The number of rows of the matrix A. Constraint: M >= 0.
  • N — INTEGER. The number of columns of the matrix A. Constraint: N >= 0.
  • A — 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 — INTEGER. The leading dimension of the array A. Constraint: LDA >= max(1,M).
  • IPIV — 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 — 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.

Author 👑

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

Definition at line 107 of file sgetrf.f.

subroutine zgetrf (integer m, integer n, complex*16, dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, integer info) — ZGETRF 💀

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

Purpose 🌙

ZGETRF computes an LU factorization of a general M-by-N matrix A using partial pivoting with row interchanges. Complex*16 main character energy, fr fr.

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 3 BLAS version of the algorithm. ✨

Parameters 🫶

  • M — INTEGER. The number of rows of the matrix A. Constraint: M >= 0.
  • N — INTEGER. The number of columns of the matrix A. Constraint: N >= 0.
  • A — 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 — INTEGER. The leading dimension of the array A. Constraint: LDA >= max(1,M).
  • IPIV — 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 — 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.

Author 👑

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

Definition at line 107 of file zgetrf.f.

Author 💖

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okay bye bestie 🫶💅 — the footer deets are LAPACK Version 3.12.0 and getrf(3); no date is printed on this page, and it’s generated automatically by Doxygen for LAPACK from the source code. periodt. 🌈

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