dgetrf.f(3)

💖 NAME 💖

dgetrf.f(3) — the LAPACK manual page for the dgetrf subroutine, bestie. This one is the left-looking Level 3 BLAS version of the algorithm. 💅

✨ SYNOPSIS ✨

🧚 Functions/Subroutines

• subroutine dgetrf (M, N, A, LDA, IPIV, INFO) — DGETRF VARIANT: left-looking Level 3 BLAS version of the algorithm.

🎀 Function/Subroutine Documentation 🎀

🦋 subroutine dgetrf

subroutine dgetrf (integer M, integer N, double precision, dimension( lda, *
       ) A, integer LDA, integer, dimension( * ) IPIV, integer INFO)

DGETRF VARIANT: left-looking Level 3 BLAS version of the algorithm.

🌈 Purpose:

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 left-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
  • = 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.

🌸 Date:

December 2016

Definition at line 102 of file VARIANTS/lu/LL/dgetrf.f.

💖 Author 💖

Generated automatically by Doxygen for LAPACK from the source code.

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💖 Cute sign-off: this iconic page is from LAPACK Version 3.8.0, dated Tue Nov 14 2017, and it's dgetrf.f(3) — bye bestie! 💅✨