TESTING/LIN/cspt01.f(3)

🎀 NAME 🎀

okay so bestie, this is the TESTING/LIN/cspt01.f(3) page from the Library Functions Manual — the file itself is TESTING/LIN/cspt01.f, and cspt01 is the main character here. no cap 💅

✨ SYNOPSIS ✨

🦋 Functions/Subroutines 🦋

       subroutine cspt01 (uplo, n, a, afac, ipiv, c, ldc, rwork, resid)
           CSPT01

💅 Function/Subroutine Documentation 💅

Here’s the exact signature tea:

   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 💖

CSPT01 reconstructs a symmetric indefinite packed matrix A from its diagonal pivoting factorization A = U*D*U' or A = L*D*L' and computes the residual

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

where C is the reconstructed matrix and EPS is the machine epsilon. literally the reconstruction + residual vibe check ✨

🌸 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. It’s 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).
• 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. The residual formula is:

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 111 of file cspt01.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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mwah 💋 sign-off time: source/version is LAPACK Version 3.12.0, and the footer’s page tag is TESTING/LIN/cspt01.f(3) — no separate date is printed in that footer, so no invented date, periodt 🫶