SRC/zlahef_aa.f(3)

✨ SRC/zlahef_aa.f ✨

okay bestie, welcome to the Library Functions Manual — section 3, iykyk — and the main character today is SRC/zlahef_aa.f(3). It’s giving Fortran subroutine energy, and we are going to read it together like the group chat is watching. 🫶

🌸 NAME 🌸

SRC/zlahef_aa.f

🦋 SYNOPSIS 🦋

Functions/Subroutines

• subroutine zlahef_aa (uplo, j1, m, nb, a, lda, ipiv, h, ldh, work) — ZLAHEF_AA

💅 Function/Subroutine Documentation 💅

subroutine zlahef_aa (...)

ZLAHEF_AA

🎯 Purpose

DLAHEF_AA factorizes a panel of a complex hermitian matrix A using the Aasen's algorithm. The panel consists of a set of NB rows of A when UPLO is U, or a set of NB columns when UPLO is L.

In order to factorize the panel, the Aasen's algorithm requires the last row, or column, of the previous panel. The first row, or column, of A is set to be the first row, or column, of an identity matrix, which is used to factorize the first panel.

The resulting J-th row of U, or J-th column of L, is stored in the (J-1)-th row, or column, of A (without the unit diagonals), while the diagonal and subdiagonal of A are overwritten by those of T.

💖 Parameters 💖

• UPLO — UPLO is CHARACTER*1; = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored. ✨
• J1 — J1 is INTEGER; the location of the first row, or column, of the panel within the submatrix of A, passed to this routine, e.g., when called by ZHETRF_AA, for the first panel, J1 is 1, while for the remaining panels, J1 is 2.
• M — M is INTEGER; the dimension of the submatrix. M >= 0. 🎀
• NB — NB is INTEGER; the dimension of the panel to be facotorized.
• A — A is COMPLEX*16 array, dimension (LDA,M) for the first panel, while dimension (LDA,M+1) for the remaining panels.

On entry, A contains the last row, or column, of the previous panel, and the trailing submatrix of A to be factorized, except for the first panel, only the panel is passed.

On exit, the leading panel is factorized. 💫

• LDA — LDA is INTEGER; the leading dimension of the array A. LDA >= max(1,N).
• IPIV — IPIV is INTEGER array, dimension (N); details of the row and column interchanges, the row and column k were interchanged with the row and column IPIV(k).
• H — H is COMPLEX*16 workspace, dimension (LDH,NB). 🦋
• LDH — LDH is INTEGER; the leading dimension of the workspace H. LDH >= max(1,M).
• WORK — WORK is COMPLEX*16 workspace, dimension (M).

👑 Author 👑

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

Definition at line 142 of file zlahef_aa.f.

🤖 Author 🤖

Generated automatically by Doxygen for LAPACK from the source code.

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💅 cute sign-off: this page is from LAPACK, Version 3.12.0, and the source/page is SRC/zlahef_aa.f(3). The footer doesn’t print a separate date, so there’s no extra date to spill — but the source, version, and page are all accounted for, bestie. 💖