TESTING/LIN/zptt01.f(3)

🦋 zptt01.f — LAPACK testing routine 🦋

okay so this is the manual page for TESTING/LIN/zptt01.f(3) — yes, a Library Functions Manual moment, and it’s literally all about one tiny subroutine. bestie, buckle up 💖

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✨ NAME ✨

TESTING/LIN/zptt01.f — that’s the name. iconic, no notes. 💅

🌸 SYNOPSIS 🌸

Functions/Subroutines

• subroutine zptt01 (n, d, e, df, ef, work, resid) — the one and only routine, also known as ZPTT01. slay. ✨

🌟 Function/Subroutine Documentation 🌟

Here’s the full signature, exactly as the source says it, bestie:

subroutine zptt01 (integer n, double precision, dimension( * ) d,
       complex*16, dimension( * ) e, double precision, dimension( * ) df,
       complex*16, dimension( * ) ef, complex*16, dimension( * ) work, double
       precision resid)

ZPTT01 — that’s the routine name. main character energy, fr fr. 🫶

🧚 Purpose 🧚

The glow-up math is literally this:

!>
!> ZPTT01 reconstructs a tridiagonal matrix A from its L*D*L'
!> factorization and computes the residual
!>    norm(L*D*L' - A) / ( n * norm(A) * EPS ),
!> where EPS is the machine epsilon.
!>

So yes: it rebuilds a tridiagonal matrix A from its L*D*L' factorization, then computes that residual. no cap, that’s the whole purpose. 🔥

🎀 Parameters 🎀

• N — N is INTEGER. The order of the matrix A. 💖
• D — D is DOUBLE PRECISION array, dimension (N). The n diagonal elements of the tridiagonal matrix A.
• E — E is COMPLEX*16 array, dimension (N-1). The (n-1) subdiagonal elements of the tridiagonal matrix A.
• DF — DF is DOUBLE PRECISION array, dimension (N). The n diagonal elements of the factor L from the L*D*L' factorization of A.
• EF — EF is COMPLEX*16 array, dimension (N-1). The (n-1) subdiagonal elements of the factor L from the L*D*L' factorization of A.
• WORK — WORK is COMPLEX*16 array, dimension (2*N). ✨
• RESID — RESID is DOUBLE PRECISION. norm(L*D*L' - A) / (n * norm(A) * EPS). 💅

👑 Author 👑

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

Definition at line 91 of file zptt01.f. 🎀

💻 Author 💻

Generated automatically by Doxygen for LAPACK from the source code.

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okay bye bestie 💋 — source/version vibes: LAPACK, Version 3.12.0, for TESTING/LIN/zptt01.f(3). mwah! 🦋💖