CHET01_ROOK(3)

🌸 NAME 🌸

hey bestie 💖 welcome to the Library Functions Manual page for TESTING/LIN/chet01_rook.f — the file that brings you CHET01_ROOK. yes, we're in testing/LIN land, and this one is lowkey iconic for matrix reconstruction vibes ✨

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✨ SYNOPSIS ✨

🫶 Functions/Subroutines

• subroutine chet01_rook (uplo, n, a, lda, afac, ldafac, ipiv, c, ldc, rwork, resid) — that's the CHET01_ROOK subroutine, bestie 🎀

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💖 Function/Subroutine Documentation 💖

okay so here's the exact signature, no cap:

subroutine chet01_rook (uplo, n, a, lda, afac, ldafac, ipiv, c, ldc,
    rwork, resid)

and the full declaration is giving very much Fortran realness:

subroutine chet01_rook (character uplo, integer n, complex, dimension( lda,
    * ) a, integer lda, complex, dimension( ldafac, * ) afac, integer
    ldafac, integer, dimension( * ) ipiv, complex, dimension( ldc, * ) c,
    integer ldc, real, dimension( * ) rwork, real resid)

this subroutine is literally called CHET01_ROOK 💅

🎯 Purpose

CHET01_ROOK reconstructs a complex Hermitian indefinite matrix A from its block L*D*L' or U*D*U' factorization and computes the residual:

norm( C - A ) / ( N * norm(A) * EPS ),

where C is the reconstructed matrix, EPS is the machine epsilon, L' is the transpose of L, and U' is the transpose of U. periodt ✨

🧚 Parameters

• UPLO — UPLO is CHARACTER*1. it tells you whether the upper or lower triangular part of the complex Hermitian matrix A is stored:

= 'U':  Upper triangular
= 'L':  Lower triangular

• N — N is INTEGER. the number of rows and columns of the matrix A. must be N >= 0 💖
• A — A is COMPLEX array, dimension (LDA,N). it's the original complex Hermitian matrix A, the main character of this whole situation 👑
• LDA — LDA is INTEGER. the leading dimension of the array A. must be LDA >= max(1,N) 🌟
• AFAC — AFAC is COMPLEX array, dimension (LDAFAC,N). this is the factored form of the matrix A. AFAC contains the block diagonal matrix D and the multipliers used to obtain the factor L or U from the block L*D*L' or U*D*U' factorization as computed by CSYTRF_ROOK 🔥
• LDAFAC — LDAFAC is INTEGER. the leading dimension of the array AFAC. must be LDAFAC >= max(1,N). 🎀
• IPIV — IPIV is INTEGER array, dimension (N). the pivot indices from CSYTRF_ROOK, slay 💅
• C — C is COMPLEX array, dimension (LDC,N). that's it, that's the whole description, bestie 🫶
• LDC — LDC is INTEGER. the leading dimension of the array C. must be LDC >= max(1,N). 🌈
• RWORK — RWORK is REAL array, dimension (N). real array energy ✨
• RESID — RESID is REAL. here's the conditional tea:

If UPLO = 'L', norm(L*D*L' - A) / ( N * norm(A) * EPS )
If UPLO = 'U', norm(U*D*U' - A) / ( N * norm(A) * EPS )

👑 Author

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

Definition at line 123 of file chet01_rook.f. iconic 📌

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💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code. no notes, it's giving auto-generated excellence 🧚‍♀️

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mwah 💋 — cute little sign-off: this page is from LAPACK Version 3.12.0, and the footer source string is TESTING/LI...et01_rook.f(3). periodt, bye bestie 🎀✨