SRC/dgetrf.f(3)

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💅 SRC/dgetrf.f — Library Functions Manual

Okay so bestie, this is the SRC/dgetrf.f(3) page from the Library Functions Manual. We're talking about DGETRF, and honestly? It's an LU factorization icon. ✨

NAME

SRC/dgetrf.f

SYNOPSIS

Functions/Subroutines

  • subroutine dgetrf (m, n, a, lda, ipiv, info) — DGETRF

Function/Subroutine Documentation

subroutine dgetrf

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

DGETRF

Purpose

Okay so DGETRF 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 3 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; the exit-status bestie:
    • = 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.

Author

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