TESTING/LIN/dptt01.f(3)

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version 3.12.1 · 3 versions
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✨ NAME ✨

Okay bestie, welcome to TESTING/LIN/dptt01.f(3) — the manual is Library Functions Manual, and this page is serving pure LAPACK test routine energy for the file TESTING/LIN/dptt01.f. That’s the name, and yes, it’s very specific. 💅

🦋 SYNOPSIS 🦋

Functions/Subroutines

  • subroutine dptt01 (n, d, e, df, ef, work, resid) — DPTT01

🌸 Function/Subroutine Documentation 🌸

Full signature, exactly as printed, no cap:

subroutine dptt01 (integer n, double precision, dimension( * ) d, double precision, dimension( * ) e, double precision, dimension( * ) df, double precision, dimension( * ) ef, double precision, dimension( * ) work, double precision resid)

And the routine name is DPTT01. Loud and proud. 👑

🌈 Purpose 🌈

DPTT01 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. That’s the whole assignment, and honestly? Iconic. ✨

🎀 Parameters 🎀

  • N — N is INTEGER. It’s the order of the matrix A. The main-character dimension, if you will. 👑
  • D — D is DOUBLE PRECISION array, dimension (N). These are the n diagonal elements of the tridiagonal matrix A. 💖
  • E — E is DOUBLE PRECISION array, dimension (N-1). These are the (n-1) subdiagonal elements of the tridiagonal matrix A. 🦋
  • DF — DF is DOUBLE PRECISION array, dimension (N). These are the n diagonal elements of the factor L from the L*D*L' factorization of A. 🌸
  • EF — EF is DOUBLE PRECISION array, dimension (N-1). These are the (n-1) subdiagonal elements of the factor L from the L*D*L' factorization of A. 💜
  • WORK — WORK is DOUBLE PRECISION array, dimension (2*N). It’s the workspace, bestie. Respect it. 🫶
  • RESID — RESID is DOUBLE PRECISION. It holds norm(L*D*L' - A) / (n * norm(A) * EPS). That’s the residual, periodt. 🔥

👑 Author 👑

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

Definition at line 90 of file dptt01.f. 📌

💜 Author 💜

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That’s the whole page, bestie: LAPACK, Version 3.12.0, for TESTING/LIN/dptt01.f(3). Mwah 💋🫶

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