TESTING/LIN/csyt01_aa.f(3)

🌸 TESTING/LIN/csyt01_aa.f(3) 🌸

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✨ NAME ✨

TESTING/LIN/csyt01_aa.f — the file, the icon, the whole manual-page moment. 🎀

🎀 SYNOPSIS 🎀

💫 Functions/Subroutines 💫

subroutine csyt01_aa (uplo, n, a, lda, afac, ldafac, ipiv, c, ldc,
           rwork, resid)

CSYT01 — that’s the subroutine name, short and iconic. ✨

🦋 Function/Subroutine Documentation 🦋

okay so here’s the full signature, bestie, and it is long but we are not skipping a crumb:

subroutine csyt01_aa (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)

CSYT01 — that’s the name, periodt. 💅

💖 Purpose 💖

okay so CSYT01 reconstructs a 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 and EPS is the machine epsilon. It’s giving “reconstruct and check,” and honestly? Obsessed. ✨

🌸 Parameters 🌸

• UPLO — UPLO is CHARACTER*1. It specifies whether the upper or lower triangular part of the 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. N >= 0.
• A — A is REAL array, dimension (LDA,N). The original hermitian matrix A.
• LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= max(1,N).
• AFAC — AFAC is REAL array, dimension (LDAFAC,N). 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.
• LDAFAC — LDAFAC is INTEGER. The leading dimension of the array AFAC. LDAFAC >= max(1,N).
• IPIV — IPIV is INTEGER array, dimension (N). The pivot indices from CSYTRF.
• C — C is REAL array, dimension (LDC,N).
• LDC — LDC is INTEGER. The leading dimension of the array C. LDC >= max(1,N).
• RWORK — RWORK is REAL array, dimension (N).
• RESID — RESID is REAL. 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 122 of file csyt01_aa.f.

👑 Author 👑

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