CSPT01(3)

💖 CSPT01(3) 💖

okay bestie, welcome to the Library Functions Manual corner of the group chat. Header vibes: CSPT01(3), path /home/abui...IN/cspt01.f(3). Today’s main character is CSPT01, a LAPACK testing subroutine that reconstructs stuff and checks the residual. No cap, it’s very “trust but verify” energy. ✨

✨ NAME ✨

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/cspt01.f — that’s the file, and CSPT01 is the subroutine living in it. Main character energy fr fr. 💅

🦋 SYNOPSIS 🦋

🧚 Functions/Subroutines 🧚

subroutine CSPT01 (uplo, n, a, afac, ipiv, c, ldc, rwork, resid)
    CSPT01

💅 Function/Subroutine Documentation 💅

subroutine CSPT01 (character uplo, integer n, complex, dimension( * ) a,
    complex, dimension( * ) afac, integer, dimension( * ) ipiv, complex,
    dimension( ldc, * ) c, integer ldc, real, dimension( * ) rwork, real
    resid)

CSPT01

🎀 Purpose 🎀

Okay so CSPT01 reconstructs a symmetric indefinite packed matrix A from its diagonal pivoting factorization A = U*D*U' or A = L*D*L', then 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 “put it back together and check the math” realness. 💖

🌸 Parameters 🌸

🔤 UPLO

• UPLO is CHARACTER*1 — 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 order of the matrix A. N >= 0.

🧩 A

• A is COMPLEX array, dimension (N*(N+1)/2) — the original symmetric matrix A, stored as a packed triangular matrix.

🗂️ AFAC

• AFAC is COMPLEX array, dimension (N*(N+1)/2) — the factored form of the matrix A, stored as a packed triangular matrix. AFAC contains the block diagonal matrix D and the multipliers used to obtain the factor L or U from the L*D*L' or U*D*U' factorization as computed by CSPTRF.

📌 IPIV

• IPIV is INTEGER array, dimension (N) — the pivot indices from CSPTRF.

🧮 C

• C is COMPLEX array, dimension (LDC,N) — that’s the whole spec, bestie.

📐 LDC

• LDC is INTEGER — the leading dimension of the array C. LDC >= max(1,N).

🧺 RWORK

• RWORK is REAL array, dimension (N) — yes, that’s all the original gives us.

🎯 RESID

• RESID is REAL — if UPLO = 'L', it’s norm(L*D*L' - A) / ( N * norm(A) * EPS ); if UPLO = 'U', it’s norm(U*D*U' - A) / ( N * norm(A) * EPS ).

👑 Author 👑

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

📍 Definition 📍

Definition at line 111 of file cspt01.f.

💫 Author 💫

Generated automatically by Doxygen for LAPACK from the source code.

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💖 That’s the whole page, bestie. Source/version energy: LAPACK Version 3.12.0, footer path /home/abui...IN/cspt01.f(3). The footer doesn’t give a separate date to shout out, so I’m not inventing one — periodt. 🫶