cgetrf.f(3)

💅 cgetrf.f(3) — LAPACK, bestie edition ✨

Okay so this is the LAPACK manual page for cgetrf.f, and we are keeping every type, flag, and caveat exactly where it belongs. No cap, fr fr. 🫶

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🌸 NAME 🌸

cgetrf.f — the cgetrf subroutine page, LAPACK-style.

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

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

🦋 Function/Subroutine Documentation 🦋

subroutine cgetrf (integer M, integer N, complex, dimension( lda, * ) A, integer LDA, integer, dimension( * ) IPIV, integer INFO)

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

💖 Purpose 💖

This one is lowkey iconic: CGETRF 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. Periodt.

🌈 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 = -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.

🚨 Heads up, bestie: that INFO > 0 case is serious — U(i,i) is exactly zero, 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 📌

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

🌟 Author 🌟

Generated automatically by Doxygen for LAPACK from the source code.

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Version 3.8.0 · Tue Nov 14 2017 · cgetrf.f(3) — generated automatically by Doxygen for LAPACK from the source code. Mwah! 💋✨